U.S. patent number 4,533,233 [Application Number 06/485,082] was granted by the patent office on 1985-08-06 for electrostatic copying apparatus.
This patent grant is currently assigned to Mita Industrial Co., Ltd.. Invention is credited to Masahiko Hisajima, Yoichiro Irie, Hiroshi Kimura, Kiyoshi Morimoto, Takashi Nagashima, Kiyoshi Shibata, Masahiro Watashi, Kiyonori Yamamoto, Toshihiko Yamamoto, Yasuhiko Yoshikawa, Shinsuke Yoshinaga.
United States Patent |
4,533,233 |
Kimura , et al. |
August 6, 1985 |
Electrostatic copying apparatus
Abstract
A variable magnification electrostatic copying apparatus
comprising a transparent plate on which to place a document to be
copied, an optical system for projecting the image of the document
onto an electrostatographic photosensitive member at any desired
projecting ratio selected from a plurality of projecting ratios in
an exposure zone located along the moving path of the
photosensitive member, and a driving means for moving at least a
part of the optical system and the transparent plate relative to
each other. The optical system includes at least one
position-variable optical element assembly adapted to be held at
any of a plurality of positions corresponding to the aforesaid
plurality of projecting ratios. The variable magnification
electrostatic copying apparatus includes a unique improved means
for varying the projecting ratio of the optical system by moving
the position-variable optical element assembly.
Inventors: |
Kimura; Hiroshi (Habikino,
JP), Hisajima; Masahiko (Osaka, JP),
Shibata; Kiyoshi (Osaka, JP), Irie; Yoichiro
(Suita, JP), Morimoto; Kiyoshi (Osaka, JP),
Nagashima; Takashi (Sakai, JP), Yoshikawa;
Yasuhiko (Ikoma, JP), Yamamoto; Kiyonori
(Neyagawa, JP), Watashi; Masahiro (Ikoma,
JP), Yoshinaga; Shinsuke (Sakai, JP),
Yamamoto; Toshihiko (Takaishi, JP) |
Assignee: |
Mita Industrial Co., Ltd.
(Osaka, JP)
|
Family
ID: |
13264695 |
Appl.
No.: |
06/485,082 |
Filed: |
April 14, 1983 |
Foreign Application Priority Data
|
|
|
|
|
Apr 20, 1982 [JP] |
|
|
57-64664 |
|
Current U.S.
Class: |
399/201; 355/55;
355/56; 355/58; 355/66; 399/202; 399/88 |
Current CPC
Class: |
G03B
27/527 (20130101); G03G 15/28 (20130101); G03G
15/041 (20130101) |
Current International
Class: |
G03B
27/52 (20060101); G03G 15/041 (20060101); G03G
15/28 (20060101); G03G 15/00 (20060101); G03G
015/28 () |
Field of
Search: |
;355/8,55,56,58,66 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Shoop, Jr.; William M.
Assistant Examiner: Ip; Shik Luen Paul
Attorney, Agent or Firm: Beveridge, DeGrandi &
Weilacher
Claims
What is claimed is:
1. A variable magnification electrostatic copying apparatus
comprising
a stationary transparent plate on which to place a document to be
copied,
an optical system for projecting the image of the document onto an
electrostatographic photosensitive member at a desired projecting
ratio selected from a plurality of projecting ratios in an exposure
zone located along the moving path of the photosensitive member,
said optical system including a first reflecting mirror assembly
adapted for reciprocation along the transparent plate, a second
reflecting mirror assembly adapted to be reciprocated in
synchronism with the reciprocation of the first reflecting mirror
assembly substantially parallel to the reciprocating direction of
the first reflecting mirror assembly and at a speed one-half of the
moving speed of the first reflecting mirror assembly, and a lens
assembly adapted to be held at any one of a plurality of positions
corresponding to the plurality of projecting ratios, the changing
of the projecting ratio being effected by changing the position of
the lens assembly and also changing the position of the second
reflecting mirror assembly relative to the first reflecting mirror
assembly in the reciprocating direction of the second reflecting
mirror assembly,
a driving means for reciprocating the first and second reflecting
mirror assemblies, and
means for varying the projecting ratio of the optical system by
moving the lens assembly and the second reflecting mirror
assembly;
wherein said projecting ratio varying means includes a driving
source, a setting member adapted to be held at any one of a
plurality of positions corresponding to the projecting ratios for
moving the second reflecting mirror assembly, a first drivingly
linking means interposed between the driving source and the lens
assembly, and a second drivingly linking means interposed between
the driving source and the setting member, and when the driving
source is operated, the lens assembly is moved and at the same
time, the setting member is moved to move the second reflecting
mirror assembly.
2. The apparatus of claim 1 wherein the first drivingly linking
means comprises at least one wrapping power transmission member,
and the second drivingly linking means comprises a cam and a cam
follower member mounted on the setting member.
3. The apparatus of claim 2 wherein the cam is constructed of a cam
plate having a plurality of arcuate positioning surfaces having
different radii on its peripheral surface, the cam follower member
is constructed of a follower roller rotatably mounted on the
setting member, and a spring member is also provided which
elastically biases the setting member to cause the follower roller
to abut elastically against the cam plate.
4. The apparatus of claim 1 wherein a decelerating interlocking
mechanism for moving the second reflecting mirror assembly in
interlocking relation to the movement of the first reflecting
mirror assembly is disposed between the first reflecting mirror
assembly and the second reflecting mirror assembly of the optical
system; the decelerating interlocking mechanism comprises a pair of
stationary pulleys rotatably mounted with a space therebetween in
the reciprocating direction of the first and second reflecting
mirror assemblies, a movable pulley mounted rotatably on the second
reflecting mirror assembly,and a rope wrapped about the pair of
stationary pulleys and the movable pulley and fixed to the first
reflecting mirror assembly; and the two free ends of the rope are
wrapped about the movable pulley in mutually opposite directions
and then linked to the setting member, and when the setting member
is moved, the movable pulley correspondingly moves to move the
second reflecting mirror assembly.
5. The apparatus of claim 4 wherein the setting member has a pair
of linking portions located on opposite sides of the movable pulley
as viewed in the reciprocating direction of the second reflecting
mirror assembly, and the two free ends of the rope are linked
respectively to the pair of linking portions.
6. The apparatus of claim 1 wherein the first drivingly linking
means includes a driven wheel and a follower wheel rotatably
mounted with a space therebetween in the moving direction of the
lens assembly, an endless wrapping power transmission member
wrapped about the driven wheel and the follower wheel, an
interlocking projection set up firmly in the wrapping power
transmission member, an interlocking member adapted to be engaged
with the interlocking projection and moved incident to the movement
of the interlocking projection, a driven member provided in the
lens assembly, an interlocking spring member interposed between the
interlocking member and the driven member for elastically biasing
the interlocking member to an interlocking relation position
relative to the driven member, an abutting projection provided in
the lens assembly, and a position setting means having a plurality
of stop portions corresponding respectively to the plurality of
positions of the lens assembly which correspond to projecting
ratios; and wherein when the driving source is operated to drive
the endless wrapping power transmission member, the motion of the
wrapping power transmission member is transmitted to the driven
member through the interlocking projection, the interlocking member
and the interlocking spring means to move the lens assembly, and
when the abutting projection abuts against any one of the plurality
of stop portions, the movement of the lens assembly is hampered,
whereupon by the motion transmitted from the wrapping power
transmission member to the interlocking member through the
interlocking projection, the interlocking member is displaced from
the interlocking relation position with respect to the driven
member against the elastic biasing action of the interlocking
spring member.
7. The apparatus of claim 6 wherein the position setting means has
stop portions located at opposite ends of the moving path of the
abutting projection and at least one intermediate stop portion
located between the two opposite ends of the moving path of the
abutting projection, and is mounted for free movement between an
operating position at which the intermediate stop portion can
hamper the movement of the abutting projection and a releasing
position at which the intermediate stop portion cannot hamper the
movement of the abutting projection, and wherein there are further
provided a spring member for elastically biasing the position
setting means to said operating position and a release means for
moving the position setting means to said releasing position
against the elastic biasing action of the spring member.
8. The apparatus of claim 7 wherein the release means is
constructed of a releasing projection provided in the interlocking
member, and when the interlocking member is displaced from the
interlocking relation position with respect to the driven member
beyond a predetermined range as a result of the abutting projecting
abutting against the intermediate stop portion of the position
setting means, the releasing projection acts on the position
setting means to move it from the operating position to the
releasing position.
9. The apparatus of claim 6 wherein the wrapping power transmission
member has a pair of linear running portions extending
substantially parallel to the moving direction of the lens
assembly; and an engaging slot extending substantially at right
angles to, and across, the pair of linear running sections of the
wrapping power transmission member is formed in the interlocking
member; and by inserting the interlocking projection into the
engaging slot, the interlocking member comes into engagement with
the interlocking projection.
10. The apparatus of claim 6 wherein the driven member has a first
and a second linking projections spaced from each other laterally
with respect to the moving direction of the lens assembly; the
interlocking member has formed therein a first and a second linking
slots for receiving the first and second linking projections
respectively; the first linking slot extends in an arcuate shape
about the second linking projection as a center, and the second
linking slot extends in an arcuate shape about the first linking
projection as a center; in said interlocking relation position, the
first and second linking projections are positioned at one ends of
the first and second linking slots respectively; and the
interlocking member can be pivotally displaced from the
interlocking relation position about the first linking projection
as a center and about the second linking projection as a
center.
11. The apparatus of claim 6 wherein when the lens assembly and the
second reflecting mirror assembly of the optical system are to be
moved to selected projecting ratio positions, the operation of the
driving source is stopped after the lapse of some time from the
time when the abutting projection has abutted against a specified
stop portion of the position setting means which corresponds to the
selected projecting ratio position, whereby the driving of the
wrapping power transmission member is stopped while the
interlocking member is displaced to some extent from the
interlocking relation position, and thus the lens assembly is
elastically held by the interlocking spring member at that position
at which the abutting projection has abutted against the specified
stop portion.
12. The apparatus of claim 11 wherein the driving source is
constructed of a reversible electric motor, and when the operation
of the motor is to be stopped, a reversing current is
instantaneously supplied to the motor to apply a braking action to
the motor.
13. The apparatus of claim 11 wherein a detection plate adapted for
rotation according to the operation of the driving source and a
detector for detecting the amount of rotation of the detection
plate are provided, and the operation of the driving source is
controlled on the basis of the amount of rotation of the detection
plate from a specified angular position corresponding to a
specified projecting ratio position selected from the plurality of
the projecting ratio positions.
14. The apparatus of claim 13 wherein the specified projecting
ratio position is a 1:1 ratio projecting position.
15. The apparatus of claim 1 wherein the driving means for
reciprocating the first and second reflecting mirror assemblies
includes a main driving source, a plurality of forward movement
clutch means disposed between the main driving source and the first
and second reflecting mirror assemblies, said clutch means being
adapted to be operated selectively according to the plurality of
projecting ratios and to move the first and second reflecting
mirror assemblies forwardly at speeds corresponding respectively to
the plurality of the projecting ratios, a backward movement clutch
means interposed between the main driving source and the first and
second reflecting mirror assemblies for moving the first and second
reflecting mirror assemblies at predetermined speeds, and a
backward movement restricting means for stopping the backward
movement of the first and second reflecting mirror assemblies fully
accurately at predetermined forward movement start positions; and
the backward movement restricting means includes a one-way clutch
having a plurality of engaging pawls on its peripheral surface and
interposed between the backward movement clutch means and the first
and second reflecting mirror asemblies, a clutch control member
freely movable between its engaging position at which it engages
one of the plurality of engaging pawls of the one-way clutch to
render the one-way clutch inoperative and its non-engaging position
at which it disengages from the engaging pawl of the one-way clutch
and renders the one-way clutch operable, a spring member for
elastically biasing the clutch control means to the non-engaging
position, and an actuating piece which moves together with the
first and second reflecting mirror assemblies, and when the first
and second reflecting mirror assemblies reach the forward movement
start positions, brings the clutch control member mechanically to
said engaging position against the elastic biasing action of the
spring member.
16. The apparatus of claim 15 wherein each of the forward movement
clutch means and the backward movement clutch means are constructed
of electromagnetic clutches.
17. The apparatus of claim 15 wherein the driving means further
includes a pair of wheels rotatably mounted with a space
therebetween in the reciprocating directions of the first and
second reflecting mirror assemblies, an endless wrapping power
transmission member wrapped about the pair of wheels, an
interlocking projection set up firmly in the endless wrapping power
transmission member, an driven member provided in the first
reflecting mirror assembly and engaged with the interlocking
projection for moving the first reflecting mirror assembly incident
to the movement of the interlocking projection, and a deceleration
interlocking mechanism for moving the second reflecting mirror
assembly in interlocking relation to the movement of the first
reflecting mirror assembly; and the output side of each of the
forward movement clutch means is drivingly connected to one of the
wheels in pair and the output side of the one-way clutch is
drivingly connected to the other wheel.
18. The apparatus of claim 17 wherein the actuating piece is
mounted on the wrapping power transmission member.
19. A variable magnification electrostatic copying apparatus
comprising
a transparent plate on which to place a document to be copied,
an optical system for projecting the image of the document on an
electrostatographic photosensitive member at a desired projecting
ratio selected from a plurality of projecting ratios in an exposure
zone located along the moving path of the photosensitive member,
said optical system containing at least one position-variable
optical element assembly adapted to be positioned at any one of a
plurality of positions corresponding to the plurality of projecting
ratios,
a driving means for moving at least a part of the optical system
and the transparent plate relative to each other, and
means for varying the projecting ratio of the optical system by
moving said position-variable optical element assembly;
wherein said projecting ratio varying means includes a driving
source, a driven wheel and a follower wheel rotatably mounted with
a space therebetween in the moving direction of the
position-variable optical element assembly, an endless wrapping
power transmission member wrapped about the driven wheel and the
follower wheel, an interlocking projection set up firmly in the
wrapping power transmission member, an interlocking member adapted
to be engaged with the interlocking projection and moved incident
to the movement of the interlocking projection, a moving member
provided in the position-variable optical element assembly, an
interlocking spring member interposed between the interlocking
member and the driven member for elastically biasing the
interlocking member to an interlocking relation position relative
to the driven member, an abutting projection provided in the
position-variable optical element assembly, and a position setting
means having a plurality of stop portions corresponding to said
plurality of positions of the position-variable optical element
assembly which correspond to the projecting ratios; and wherein
when the driving source is operated to drive the endless wrapping
power transmission member, the motion of the wrapping power
transmission member is transmitted to the driven member through the
interlocking projection, the interlocking member and the
interlocking spring member to move the position-variable optical
element assembly, and when the abutting projection abuts against
any one of the plurality of stop portions, the movement of the
position-variable optical element assembly is hampered, whereupon
by the motion transmitted from the wrapping power transmission
member to the interlocking member through the interlocking
projection, the interlocking member is displaced from the
interlocking relation position with respect the the driven member
against the elastic biasing action of the interlocking spring
member.
20. The apparatus of claim 19 wherein the position setting means
has stop portion located at opposite ends of the moving path of the
abutting projection and at least one intermediate stop portion
located between the two opposite ends of the moving path of the
abutting projection, and is mounted for free movement between an
operating position at which the intermediate stop portion can
hamper the movement of the abutting projection and a releasing
position at which the intermediate stop portion cannot hamper the
movement of the abutting projection, and wherein there are further
provided a spring member for elestically biasing the position
setting means to said operating position and a release means for
moving the position setting means to said releasing position
against the elastic biasing action of the spring member.
21. The apparatus of claim 20 wherein the release means is
constructed of a releasing projection provided in the interlocking
member, and when the interlocking member is displaced from the
interlocking relation position with respect to the driven member
beyond a predetermined range as a result of the abutting projection
abutting against the intermediate stop portion of the position
setting means, the releasing projection acts on the position
setting means to move it from the operating position to the
releasing position.
22. The apparatus of claim 19 wherein the wrapping power
transmission member has a pair of linear running sections extending
substantially parallel to the moving direction of the
position-variable optical element assembly; and an engaging slot
extending substantially at right angles to, and across, the pair of
linear running sections of the wrapping power transmission member
is formed in the interlocking member; and by inserting the
interlocking projection into the engaging slot, the interlocking
member comes into engagement with the interlocking projection.
23. The apparatus of claim 19 wherein the driven member has a first
and a second linking projections spaced from each other laterally
with respect to the moving direction of the position-variable
optical element assembly; the interlocking member has formed
therein a first and a second linking slots for receiving the first
and second linking projections respectively; the first linking slot
extends in an arcuate shape about the second linking projection as
a center, and the second linking slot extends in an arcuate shape
about the first linking projection as a center; in said
interlocking relation position, the first and second linking
projections are positioned at one ends of the first and second
linking slots respectively; and the interlocking member can be
pivotally displaced from the interlocking relation position about
the first linking projection as a center and about the second
linking projection as a center.
24. The apparatus of claim 19 wherein when the position-variable
optical element assembly is to be moved to a selected projection
ratio position, the operation of the driving source is stipped
after the lapse of some time from the time when the abutting
projection has abutted against a specified stop portion of the
position setting means which corresponds to the selected projection
ratio position, whereby the driving of the wrapping power
transmission member is stopped while the interlocking member is
displaced to some extent from the interlocking relation position,
and thus the position-variable optical element assembly is
elastically held by the interlocking spring member at that position
at which the abutting projection has abutted against the specified
stop portion.
25. The apparatus of claim 24 wherein the driving source is
constructed of a reversible electric motor, and when the operation
of the motor is to be stopped, a reversing current is
instantaneously supplied to the motor to apply a braking action to
the motor.
26. The apparatus of claim 24 wherein a detection plate adapted for
rotation according to the operation of the driving source and a
detector for detecting the amount of rotation of the detection
plate are provided, and the operation of the driving source is
controlled on the basis of the amount of rotation of the detection
plate from a specified angular position corresponding to a
specified position selected from the plurality of the projecting
ratio positions.
27. The apparatus of claim 26 wherein the specified projecting
ratio position is a 1:1 ratio projecting position.
28. An electrostatic copying apparatus comprising
a transparent plate on which to place a document to be copied,
an optical system for projecting the image of the document onto an
electrostatographic photosensitive member in an exposure zone
located along the moving path of the photosensitive member, and
a driving means for reciprocating one of at least a part of the
optical system and the transparent plate, said driving means
including a main driving source, at least one forward movement
clutch interposed between the main driving source and said one of
at least a part of the optical system and the transparent plate for
moving said one of at least a part of the optical system and the
transparent plate forward, and a backward movement clutch
interposed between the main drive source and said one of at least a
part of the optical system and the transparent plate for moving
said one of at least a part of the optical system and the
transparent plate backward;
wherein said driving means further includes a backward movement
restricting means for stopping the backward movement of said one of
at least a part of the optical system and the transparent plate
fully accurately at a predetermined forward movement start
position, and said backward movement restricting means includes a
one-way clutch having a plurality of engaging pawls on its
peripheral surface and interposed between the backward movement
clutch means and said one of at least a part of the optical system
and the transparent plate, a clutch control member freely movable
between its engaging position at which it engages one of the
plurality of engaging pawls of the one-way clutch to render the
one-way clutch inoperative and its non-engaging position at which
it disengages from the engaging pawl of the one-way clutch and
renders the one-way clutch operable, a spring member for
elastically biasing the clutch control member to the non-engaging
position, and an actuating piece which moves together with said one
of at least a part of the optical system and the transparent plate,
and when said one of at least a part of the optical system and the
transparent plate reaches the forward movement start position,
brings the clutch control member mechanically to said engaging
position against the elastic biasing action of the spring
member.
29. The apparatus of claim 28 wherein the forward movement clutch
means and the backward movement clutch means are constructed of
electromagnetic clutches.
30. The apparatus of claim 28 wherein the driving means further
includes a pair of wheels rotatably mounted with a space
therebetween in the reciprocating direction of said one of at least
a part of the optical system and the transparent plate, an endless
wrapping power transmission member wrapped about the pair of
wheels, an interlocking projection set up firmly in the endless
wrapping power transmission member, and a driven member provided in
said one of at least a part of the optical system and the
transparent plate and engaged with the interlocking projection for
moving said one of at least a part of the optical system and the
transparent plate incident to the movement of the interlocking
projection; and wherein the output side of each of said forward
movement clutch means is drivingly connected to one of the wheels
in pair, and the output side of the one-way clutch is drivingly
connected to the other wheel.
31. The apparatus of claim 30 wherein the actuating piece is
mounted on the wrapping power transmission member.
Description
FIELD OF THE INVENTION
This invention relates to an electrostatic copying apparatus, and
more specifically, to a variable magnification electrostatic
copying apparatus capable of producing copies at any of a plurality
of magnification ratios.
DESCRIPTION OF THE PRIOR ART
Variable magnification electrostatic copying apparatuses capable of
producing copies of a document at a desired magnification ratio
selected from a plurality of magnification ratios, for example a
1:1 ratio or on a reduced or enlarged scale at a given
magnification ratio, have been proposed and come into commercial
acceptance.
Such a variable magnification electrostatic copying apparatus
generally has an optical system capable of projecting the image of
a document placed on a transparent plate at a selected projecting
ratio on a photosensitive member in an exposure zone along the
moving path of the photosensitive member. The copying magnification
can generally be varied by changing the projecting ratio of the
optical system and the speed of scanning exposure which is carried
out by moving at least a part of the optical system and the
transparent plate relative to each other. The projecting ratio of
the optical system can be changed by changing the position of at
least one optical element assembly of the optical system. When the
optical system is of the type which includes a first reflecting
mirror assembly, a second reflecting mirror assembly and a lens
assembly and in which at the time of scanning exposure, the first
reflecting mirror assembly is moved along the stationary
transparent plate and in synchronism with the movement of the first
reflecting mirror assembly, the second reflecting mirror assembly
is moved at a speed one-half of that of the first reflecting mirror
assembly, the projecting ratio of the optical system can be changed
by changing the position of the lens assembly and the position of
the second reflecting mirror assembly with respect to the first
reflecting mirror assembly.
However, the conventional variable magnification electrostatic
copying apparatuses have problems or defects which have to be
overcome. For example, (a) when the optical system is of the
aforesaid type, means for changing the projecting ratio of the
optical system by moving the optical element assemblies, i.e. the
lens assembly and the second reflecting mirror assembly is
relatively complex and costs high; and (b) the optical element
assemblies, particularly the lens assembly and the second
reflecting mirror assembly in the optical system of the aforesaid
type, whose position is to be changed for changing the projecting
ratio of the optical system, cannot be held at a required position
fully accurately and stably. Furthermore, in electrostatic copying
apparatuses in general not restricted to those having the function
of performing variable magnification copying, it is important that
at least a part of the optical system or the transparent plate
which is to be moved for scanning exposure should be accurately
held at a specified position, namely a forward movement start
position, after the required movement. In the conventional
electrostatic copying apparatuses, there is a tendency that at
least a part of the optical system or the transparent plate cannot
be held at a specified start-of-forward movement position fully
accurately and stably. This tendency is especially pronounced when
the apparatus is operated continuously over a long period of
time.
SUMMARY OF THE INVENTION
It is a primary object of this invention therefore to provide an
improved variable magnification electrostatic copying apparatus
equipped with an optical system of the aforesaid type in which
means for changing the projecting ratio of the optical system by
moving optical element assemblies, i.e. a lens assembly and a
second reflecting mirror assembly, as required has sufficient
reliability and yet is relatively simple and costs low.
Another object of this invention is to provide an improved variable
magnification electrostatic copying apparatus in which optical
element assemblies, specifically a lens assembly and a second
reflecting mirror assembly in the case of an optical system of the
aforesaid type, whose position is to be changed by changing the
projecting ratio of the optical system, can be held at a required
position fully accurately and stably.
Still another object of this invention is to provide an improved
electrostatic copying apparatus in which at least a part of an
optical system or a transparent plate to be moved for scanning
exposure can be held at a specified forward movement start position
fully accurately and stably after its required movement.
Further objects of this invention will become apparent from the
following description made with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified sectional view showing one embodiment in its
entirety of the variable magnification electrostatic copying
apparatus constructed in accordance with this invention;
FIG. 2 is a partial perspective view showing a first and a second
reflecting mirror assembly of an optical system in the
electrostatic cipying apparatus shown in FIG. 1;
FIG. 3 is a partial perspective view showing a lens assembly and
means for changing the projecting ratio of an optical system in the
electrostatic copying apparatus shown in FIG. 1;
FIGS. 4-A, 4-B, 4-C, 4-D and 4-E are partial simplified views for
illustrating the action of the means for changing the projecting
ratio of the optical system;
FIG. 5 is a block diagram showing one example of a circuit for
controlling a driving source for the means for changing the
projecting ratio of the optical system;
FIG. 6 is a partial perspective view showing, partly in a
simplified from, driving means for reciprocating the first and
second reflecting mirror assemblies of the optical system in the
electrostatic copying apparatus shown in FIG. 1; and
FIG. 7 is a partial sectional view showing a backward movement
restricting means used in the driving means shown in FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention is described below in detail with reference to the
accompanying drawings showing the preferred embodiments of the
variable magnification electrostatic copying apparatus of the
invention.
General Structure of the Copying Apparatus
The general structure of the variable magnification copying
apparatus of this invention is first described with reference to
FIG. 1 which illustrates in a simplified form the entire view of
one embodiment of the electrostatic copying apparatus of this
invention.
The illustrated copying apparatus has a nearly rectangular housing
shown generally at 2. A stationary transparent plate 4 on which to
place a document to be copied is fixed to the upper surface of the
housing 2, and an openable and closable document presser 5 for
covering the transparent plate 4 and a document placed thereon is
provided on the top surface of the housing 2.
Within the housing 2 is provided a base plate 6 most of which
extends substantially horizontally within the housing 2 to divide
the inside of the housing 2 into an upper space and a lower space.
A cylindrical rotating drum 8 is rotatably mounted nearly centrally
in the lower space. An electrostatographic photosensitive material
10 is disposed on at least a part of the peripheral surface of the
rotating drum 8.
Around the rotating drum 8 to be rotated in the direction of an
arrow 12 are disposed a charging corona discharge device 14, a
charge eliminating lamp 16, a developing device 18, a transferring
corona discharge device 20, a peeling corona discharge device 22
and a cleaning device 24 in this order in the rotating direction of
the rotating drum 8. The charging corona discharge device 14
substantially uniformly charges the photosensitive member 10 to a
specified polarity. An exposure zone 26 exists between the charging
corona discharge device 14 and the charge eliminating lamp 16. In
the exposure zone 26, the image of a document placed on the
transparent plate 4 is projected onto the photosensitive member 10
by an optical system to be described, thereby forming a latent
electrostatic image corresponding to the image of the document. The
charge eliminating lamp 16, in a reduced scale copying mode, etc.,
illuminates the two side portions of the photosensitive member 10
(the two side portions viewed in the direction of the central axis
of rotation of the rotating drum 8) which have been charged by the
charging corona discharge device 14 but onto which the image of the
document has not been projected in the exposure zone 26, thereby
removing the charge on the aforesaid two side portions. The
developing device 18 applies toner particles to the latent
electrostatic image formed on the photosensitive member 10 to
develop it into a toner image. The transferring corona discharge
device 20 applies corona discharge to the back of a copying paper
kept in contact with the surface of the photosensitive member 10 in
a transfer zone 28 to transfer the toner image on the
photosensitive member 10 to the copying paper. The peeling corona
discharge device 22 applies corona discharge to the back of the
copying paper immediately downstream of the transfer zone 28 to
peel the copying paper from the surface of the photosensitive
member 10 to which it adheres electrostatically. The cleaning
device 24 has a blade 30 made of an elastic material capable of
being pressed against the surface of the photosensitive member 10,
and by the action of the blade 30, residual toner particles on the
photosensitive member 10 are removed. If desired, a charge
eliminating lamp and a charge-eliminating corona discharge device
(not shown) for removing residual charges which will remain on the
photosensitive member 10 after transfer may be additionally
provided in a zone between the peeling corona discharge device 22
and the cleaning device 24 in the rotating direction of the
rotating drum 8 as shown by arrow 12.
In the lower portion of the housing 2, there are provided two paper
feed mechanisms 32a and 32b placed side by side in the vertical
direction and a paper conveying mechanism shown generally at 34 for
conveying a copying paper fed from the paper feed mechanisms 32a
and 32b through the transfer zone 28. The paper feed mechanisms 32a
and 32b respectively have cassette-receiving sections 36a and 36b,
paper cassettes 38a and 38b to be mounted detachably on the
cassette-receiving sections 36a and 36b through openings formed in
the right-side wall of the housing 2, and delivery rollers 40a and
40b. One of the delivery rollers 40a and 40b is selectively
actuated to deliver copying papers one by one from a plurality of
sheet-like copying papers stacked in the paper cassette 38a or 38b
to the paper conveying mechanism 34 through a delivery passage 42a
or 42b. The paper feed mechanism 34 includes a carrying roller unit
44, a guide plate unit 46 and a conveying roller unit 48 for
conveying the paper delivered through the delivery passage 42a or
42b, a guide plate unit 50 for conducting the copying paper from
the conveyor roller unit 48 to the transfer zone 28, a conveying
belt assembly 52 for conveying the copying paper peeled from the
photosensitive member 10, a fixing roller unit 54, a guide plate
unit 55, a discharge roller unit 56 and a receiving tray 58 for
receiving the copying paper discharged from the discharge roller
unit 56 through an opening formed in the left-side wall of the
housing 2. A set of rollers in the fixing roller unit 54 which are
located in an upper portion thereof have a heating element (not
shown) inside, and press and heat the surface of the copying paper
having the toner image transferrred from the photosensitive member
10, thereby fixing the toner image to the copying paper.
An optical system shown generally at 60 for projecting the image of
a document placed on the transparent plate 4 onto the
photosensitive member 10 in the exposure zone 26 is provided in the
upper space of the housing 2 above the base plate 6. This optical
system 60 is comprised of a first reflecting mirror assembly 66
having a document illuminating lamp 62 and a reflecing mirror 64, a
second reflecting mirror assembly 72 having two reflecting mirrors
68 and 70, a lens assembly 74 having at least one lens, and a third
reflecting mirror assembly 78 having a reflecting mirror 76. As
stated in detail hereinafter, the first reflecting mirror assembly
66 is reciprocated in the left and right directions in FIG. 1 along
the transparent plate 4. The second reflecting mirror assembly 72
is reciprocated in the left and right directions in FIG. 1 in
synchronism with the reciprocation of the first reflecting mirror
assembly 66 substantially parallel to the reciprocating direction
of the first reflecting mirror assembly 66 at a speed one-half of
the moving speed of the first reflecting mirror assembly 66. When
the first reflecting mirror assembly 66 and the second reflecting
mirror assembly 72 move forwardly from left to right in FIG. 1, the
document placed on the transparent plate 4 is scanned, and the
image of the document is projected onto the photosensitive member
10 in the exposure zone 26. The reflected light from the document
illuminated by the document illuminating lamp 62 is reflected by
the reflecting mirrors 64, 68 and 70, passes through the lens of
the lens assembly 74, thereafter is reflected by the reflecting
mirror 76, passes through an opening 80 formed in the base plate 6,
and finally arrives at the photosensitive member 10 in the exposure
zone 26. Between the opening 80 and the photosensitive member 10 is
disposed a slit exposure width-restricting member 82 for
restricting the slit exposure width which is the width of a light
path leading to the photosensitive member 10 in the moving
direction of the photosensitive member 10 (i.e., in the rotating
direction of the rotating drum 8 shown by arrow 12).
The illustrated copying apparatus is constructed such that copies
can be produced at a magnification ratio selected from four
magnification ratios, i.e. a 1:1 ratio copying, a first reduced
copying shown by a length ratio of about 0.82 and an area ratio of
about 0.67, a second reduced copying shown by a length ratio of
about 0.7 and an area ratio of about 0.5, and an enlarged copying
shown by a length ratio of about 1.27 and an area ratio of about
1.6.
In the case of the 1:1 ratio copying, the lens assembly 74 of the
optical system 60 is held at a position shown by a solid line in
FIG. 1, and the second reflecting mirror assembly 72 is held at a
position shown by a solid line in FIG. 1 at the start of forward
movement. Thus, the optical system 60 is in condition for
projecting the image of a document at a ratio of 1:1 onto the
photosensitive member 10. When the optical system 60 projects the
image of the document onto the photosensitive member 10, the first
reflecting mirror assembly 66 is moved forwardly at a speed V
substantially equal to the moving speed of the photosensitive
member 10, and the second reflecting mirror assembly 72 is moved
forward at a speed of V/2.
In the case of the first reduced copying mentioned above, the lens
assembly 74 of the optical system 60 is held at a first reduction
position shown by a two-dot chain line 74R.sub.1 in FIG. 1, and the
second reflecting mirror assembly 72 is held at a first reduction
position shown by a tow-dot chain line 72R.sub.1 in FIG. 1 at the
start of its forward movement. Thus, the optical system 60 is in
condition for projecting the image of the document at a ratio of
about 0.82 onto the photosensitive member 10 (whereby the size of a
latent electrostatic image formed on the photosensitive member 10
in the widthwise direction is reduced to about 0.82 times the
actual size of the document). When the image of the document is
projected onto the photosensitive member 10, the first reflecting
mirror assembly 66 is moved at a speed of about V/0.82, and the
second reflecting mirror assembly 72 is moved at a speed of about
V/(2.times.0.82) (whereby the size of a latent electrostatic image
formed on the photosensitive member 10 in the moving direction of
the photosensitive member 10, namely in the scan exposure moving
direction, is reduced to about 0.82 times the actual size of the
document).
In the case of the second reduced copying, the lens assembly 74 of
the optical system 60 is held at a second reduction position shown
by a two-dot chain line 74R.sub.2 in FIG. 1, and the second
reflecting mirror assembly 72 is held at a second reduction
position shown by a two-dot chain line 72R.sub.2 in FIG. 1 at the
start of its forward movement. Thus, the optical system 60 is in
condition for projecting the image of the document at a
magnification ratio of about 0.7 onto the photosensitive member 10
(whereby the size of a latent electrostatic image formed on the
photosensitive member 10 in the widthwise direction is reduced to
about 0.7 times the actual size of the document). When the image of
the document is projected onto the photosensitive member 10, the
first reflecting mirror assembly 66 is moved at a speed of about
V/0.7, and the second reflecting mirror assembly 72 is moved at a
speed of about V/(2.times.0.7) (whereby the size of a latent
electrostatic image formed on the photosensitive member 10 in the
moving direction of the photosensitive member 10, namely the scan
exposure moving direction, is reduced to about 0.7 times the actual
size of the document).
In the enlarged copying mode, the lens assembly 74 of the optical
system 60 is held at an enlargement position shown by a two-dot
chain line 74E in FIG. 1, and the second reflecting mirror assembly
72 is held at an enlargement position shown by a tow-dot chain line
72E in FIG. 1 at the start of its forward movement. Thus, the
optical system 60 is in condition for projecting the image of the
document at a magnification ratio of about 1.27 onto the
photosensitive member 10 (whereby the size of a latent
electrostatic image formed on the photosensitive member 10 in the
widthwise direction is enlarged to about 1.27 times the actual size
of the document). When the image of the document is projected onto
the photosensitive member 10, the first reflecting mirror assembly
66 is moved at a speed of about V/1.27, and the second reflecting
mirror assembly 72, at a speed of about V/(2.times.1.27) (whereby
the size of a latent electrostatic image formed on the
photosensitive member 10 in the moving direction of the
photosensitive member 10, namely its scan exposure moving
direction, is enlarged to about 1.27 times the actual size of the
document).
On the other hand, the rotating drum 8 is rotated at a
predetermined speed always irrespective of the copying
magnification ratio, and thus the photosensitive member 10 is
always moved at a speed V. The paper conveying mechanism 34 conveys
papers through the transfer zone 28 always at a predetermined
speed, i.e. at the same speed as the moving speed of the
photosensitive member 10, irrespective of the copying magnification
ratio.
The aforesaid structure of the illustrated variable magnification
electrostatic copying apparatus has already been known, and only
shows one example of variable magnification electrostatic copying
machines to which the present invention is applicable.
In the illustrated variable magnification electrostatic copying
apparatus, the following improvements have been made in regard to
the optical system 60.
First and Second Reflecting Mirror Assemblies
With reference to FIG. 2 which is a perspective view seen from the
side of a forward movement start position (left side in FIG. 1),
which shows the first reflecting mirror assembly 66 and the second
reflecting mirror assembly 72 as they have been moved forwardly a
considerable distance from the forward movement start positions, a
pair of mounting brackets 84 and 86 are fixed in the upper space of
the housing 2 above the base plate 6 (FIG. 1) with a space
therebetween in the reciprocating directions (the left and right
directions in FIG. 1) of the first reflecting mirror assembly 66
and the second reflecting mirror assembly 72. Furthermore, a pair
of mounting brackets 88 and 90 are fixed which are spaced from each
other in the aforesaid reciprocating directions and also spaced
widthwise (in the direction perpendicular to the sheet surface in
FIG. 1) from the aforesaid pair of mounting brackets 84 and 86. A
suspending rod 92 is fixed between the mounting brackets 84 and 86,
and a suspending rod 94, between the mounting brackets 88 and 90. A
mounting bracket 96 is fixed substantially midway between the pair
of mounting brackets 84 and 86, and a suspending rod 98 is fixed
between the mounting brackets 96 and 84.
On the other hand, the first reflecting mirror assembly 66 has a
support frame 100 on which the document illuminating lamp 62 and
the reflecting mirror 64 are mounted in position. A sliding block
102 is fixed to one end of the support frame 100, and slidably
mounted on the suspending rod 92. A roller 104 is rotatably mounted
on the other end of the support frame 100 and is also placed on the
suspending rod 94. Thus, the first reflecting mirror assembly 66
having the document illuminating lamp 62 and the reflecting mirror
64 is mounted for free sliding along the suspending rods 92 and
94.
The second reflecting mirror assembly 72 also has a support frame
106 to which the reflecting mirror 68 and the reflecting mirror 70
are fixedly secured in position. A sliding block 108 is fixed to
one end of the support frame 106, and also slidaly mounted on the
suspending rod 98. A roller 110 is rotatably mounted on the other
end of the support frame 106, and placed on the suspending rod 94.
Thus, the second reflecting mirror assembly 72 having the
reflecting mirrors 68 and 70 is mounted for free sliding along the
suspending rods 98 and 94.
A driven member 116 having a widthwise protruding horizontal
portion 112 and a suspending portion 114 extending downwardly from
the protruding end of the horizontal portion 112 is fixed by means
of a pair of setscrews 117 to the sliding block 102 fixed to one
end of the first reflecting mirror assembly 66. A driving force for
reciprocating the first relecting mirror assembly 66 is transmitted
to the driven member 116, whereby the first reflecting mirror
assembly 66 is reciprocated along the suspending rods 92 and 94, as
will be described in detail hereinafter.
Between the first reflecting mirror assembly 66 and the second
reflecting mirror assembly 72 is disposed a decelerating
interlocking mechanism shown generally at 118 for reciprocating the
second reflecting mirror assembly 72 at a speed one-half of the
moving speed of the first reflecting mirror assembly 66 in
interlocking relation to the reciprocation of the first reflecting
mirror assembly 66. The illustrated deceleration interlocking
mechanism 118 includes a pair of stationary pulleys 120 and 122, a
movable pulley 124, and a rope 126 wrapped about these pulleys 120,
122 and 124. The pair of stationary pulleys 120 and 122 are
rotatably mounted on support shafts 128 and 130 which are
respectively fitted in an upstanding base plate (not shown) within
the housing 2 and are spaced from each other in the reciprocating
directions of the first reflecting mirror assembly 66 and the
second reflecting mirror assembly 72. On the other hand, the
movable pulley 124 is rotatably mounted on a support shaft 132
fitted in a bracket 131 fixed to the sliding block 108 which in
turn is fixed to one end of the support frame 106 of the second
reflecting mirror 72. In the illustrated embodiment, an elongated
setting member 134 extending in the reciprocating directions of the
first reflecting mirror assembly 66 and the second reflecting
mirror 72 is provided in relation to the deceleration interlocking
mechanism 118 including the pair of stationary pulleys 120 and 122,
the movable pulley 124 and the rope 126. Slots 136 and 138
extending in the aforesaid reciprocating directions are formed in
the opposite end portions of the setting member 134, and support
shafts 140 and 142 provided in the aforesaid upstanding base plate
(not shown) are received respectively in the slots 136 and 138.
Thus, the setting member 134 is mounted movably in the
receiprocating directions. As will be described in detail
hereinafter, the setting member 134 is adapted to be selectively
held at any of four different positions according to a copying
magnification ratio selected. A pair of linking portions 144 and
146 conveniently positioned on opposite sides of the movable pulley
124 are formed in the setting members 134. The rope 126 extends
from its one end fixed to the linking portion 144 of the setting
member 134 toward the movable pulley 124, is wrapped about the
movable pulley 124, then extends toward the driven member 116 fixed
to one end of the first reflecting mirror assembly 66 and fixed to
the driven member 116 at a position shown by 148. The rope 126
further extends toward the stationary pulley 120, is wrapped about
it, then extends toward the stationary pulley 122 and is wrapped
about it, and thereafter extends further toward the movable pulley
124 and is wrapped about the movable pulley 124 in a direction
opposite to the first-mentioned wrapping direction. It further
extends to the linking portion 146 of the setting member 134 and
its other end is fixed to it.
It will be readily appreciated that because of the presence of the
deceleration interlocking mechanism 118, when the first reflecting
mirror assembly 66 is moved forwardly in the direction of an arrow
150, the second reflecting mirror assembly 72 is moved forwardly in
interlocking relation to it in the direction of the arrow 150 at a
moving speed one-half of the moving speed of the first reflecting
mirror assembly 66, and likewise when the first reflecting mirror
assembly 66 is moved backwardly in the direction of an arrow 152,
the second reflecting mirror assembly 72 is moved backwardly in
interlocking relation to it in the direction of the arrow 152 at a
speed one-half of the moving speed of the first reflecting mirror
assembly 66.
Furthermore, attention must be given to the following fact with
regard to the deceleration interlocking mechanism 118 and the
setting member 134. When the setting member 134 is moved in the
direction of arrow 150 while the driving of the first reflecting
mirror assembly 66 is suspended, the movable pulley 124 moves in
the direction of arrow 150 according to the movement of the setting
member 134 in the direction of arrow 150 while rotating clockwise
as seen from left bottom in FIG. 2, and thus, the second reflecting
mirror assembly 72 is moved in the direction of arrow 150 with
respect to the first reflecting mirror assembly 66 by a distance
one-half of the moving distance of the setting member 134 as the
setting member 134 moves in the direction of arrow 150. This is
because the first reflecting mirror assembly 66 is kept from moving
because the driven member 116 fixed thereto is drivingly connected
to a driving means as will be described hereinafter. Likewise, when
the setting member 134 is moved in the direction of arrow 152 while
the driving of the first reflecting mirror assembly 66 is
suspended, the movable pulley 124 is moved in the direction of
arrow 152, while rotating counterclockwise as seen from left bottom
in FIG. 2, according to the movement of the setting member 134 in
the direction of arrow 152. Thus, the second reflecting mirror
assembly 72 is moved in the direction of arrow 152 with respect to
the first reflecting mirror assembly 66 by a distance one-half of
the moving distance of the setting member 134 according to the
movement of the setting member 134 in the direction of arrow 152.
The above movement of the second reflecting mirror assembly 72
according to the movement of the setting member 134 is utilized in
changing the position of the second reflecting mirror assembly 72
when the projecting ratio of the optical system 60 (FIG. 1) is to
be varied, as will be described in detail hereinafter.
Lens Assembly
With reference to FIG. 3, a pair of brackets 154 and 156 are fixed
to the base plate 6 (FIG. 1) within the housing 2 with a space
therebetween in the reciprocating directions (the left and right
directions in FIG. 1) of the first reflecting mirror assembly 66
and the second reflecting mirror assembly 72. A suspending rod 158
is fixed between the brackets 154 and 156.
The lens assembly 74 has a support block 160 to which a lens member
162 having at least one lens is fixed. The lens member 162 has a
cylindrical lens housing 164. A linking sleeve 168 having a linking
projection 166 is received about the lens housing 164 and fixed to
the lens housing 164 by means of a setscrew 170. On the other hand,
an upstanding piece 172 is formed on the support block 160, and the
lens member 162 is fixed to the support block 160 by fixing the
linking projection 166 of the linking sleeve 168 to the upstanding
piece 172 by means of a setscrew 174. One end portion of the
support block 160 of the lens assembly 74 is slidably mounted on
the suspending rod 158, and a downwardly extending suspending piece
176 is formed at the other end of the support block 160. The lower
end of the suspending piece 176 is kept in contact with the upper
surface of the base plate 6 (FIG. 1) provided within the housing 2.
Thus, the lens assembly 74 is mounted slidably along the suspending
rod 158.
To one end portion of the support block 160 of the lens assembly 74
is fixed a driven member 178 extending widthwise from there by
means of a pair of setscrews 180. As will be described in detail
hereinafter, a driving force is transmitted to the driven member
178 to move the lens assembly 74 along the suspending rod 158 for
changing the projecting ratio of the optical system 60 (FIG.
1).
Means for Varying the Projecting Ratio of the Optical System
The illustrated variable magnification electrostatic copying
apparatus in accordance with this invention is constructed such
that it can produce copies at a copying magnification ratio
selected from a 1:1 ratio, a first reduced ratio (a length ratio of
about 0.82 and an area ratio of about 0.67), a second reduced ratio
(a length ratio of about 0.7 and an area ratio of about 0.5), and
an increased ratio (a length ratio of about 1.27 and an area ratio
of about 1.6). In the case of the 1:1 ratio, the lens assembly 74
and the second reflecting mirror assembly 72 are held at the
positions shown by solid lines in FIG. 1. In the case of copying at
the first reduced ratio, the lens assembly 74 and the second
reflecting mirror assembly 72 are held at the positions shown by
two-dot chain lines 74R.sub.1 and 72R.sub.1 in FIG. 1. In the case
of copying at the second reduced ratio, the lens assembly 74 and
the second reflecting mirror assembly 72 are held at the positions
shown by two-dot chain lines 74R.sub.2 and 72R.sub.2 in FIG. 1. In
the case of copying at the increased ratio, the lens assembly 74
and the second reflecting mirror assembly 72 are held at the
positions shown by two-dot chain lines 74E and 72E in FIG. 1. The
positioning of the lens assembly 74 and the second reflecting
mirror assembly 72 as described above is effected when the
reciprocations of the first reflecting mirror assembly 66 and the
second reflecting mirror assembly 72 are suspended and these
assemblies 66 and 72 are held at their forward movement start
positions. Hence, the positions of the second reflecting mirror
assembly 72 shown by the solid line and the two-dot chain lines
72R.sub.1, 72R.sub.2 and 72E in FIG. 1 are its positions at which
it is held at the start of forward movement.
The illustrated variable magnification electrostatic copying
apparatus constructed in accordance with this invention has means
182 for varying the projecting ratio of the optical system, which
is adapted to hold the lens assembly 74 at a selected position
among the four aforesaid positions and also the second reflecting
mirror assembly 72 at a selected position among the aforesaid four
positions in accordance with the selected copying magnification
ratio.
With reference to FIG. 3, the illustrated projecting ratio varying
means 182 includes a driving source 184 which is conveniently a
reversible electric motor. The output shaft (not shown) of the
driving source 184 is connected to the input shaft (not shown) of a
decelerator 186, and a gear 200 is fixed to the output shaft 188 of
the decelerator 186. The gear 200 is drivingly connected to a gear
204 via a gear 202. The gear 204 is fixed to an upstanding rotating
shaft 206 rotatably mounted on the base plate 6 (FIG. 1). To the
rotating shaft 206 are also fixed a cam plate 208 located above the
gear 204, a detection plate 210 located below the gear 204, and a
toothed pulley 212 located below the detection plate 210. As will
be understood from the following description, the toothed pulley
212 constitutes an input element of a first drivingly connecting
means interposed between the lens assembly 74 and the gear 204
rotated by the driving source 184; the cam plate 208 constitutes an
input element of a second drivingly connecting means interposed
between the gear 204 and the setting member 134; and the detection
plate 210 cooperates with two detectors to be described
hereinbelow.
The first drivingly connecting means interposed between the gear
204 and the lens assembly 74 will be described. A pair of
upstanding rotating shafts 214 and 216 are rotatably mounted on the
base plate 6 (FIG. 1) with a space therebetween in the longitudinal
direction of the suspending rod 158, i.e. in the moving direction
of the lens assembly 74. A driven wheel 218 which is conveniently a
sprocket wheel and a toothed pulley 220 located below the driven
wheel 218 are fixed to the rotating shaft 214, and a follower wheel
222 which is conveniently a sprocket wheel is fixed to the rotating
shaft 216. An endless toothed belt 224 is wrapped about the toothed
pulley 212 constituting the input element of the first drivingly
connecting means and the toothed pulley 220 fixed to the rotating
shaft 214. An endless wrapping power transmission member 226
composed of an endless chain is wrapped about the driven wheel 218
and the follower wheel 222. The wrapping power transmission member
226 has a pair of linear running sections 226a and 226b extending
substantially parallel to the moving direction of the lens assembly
74.
On the other hand, the moving member 178 is fixed to the lens
assembly 74 as stated hereinabove. To the driven member 178 is
connected an interlocking member 232 through an interlocking spring
member composed of two pull spring members 228 and 230. A pair of
linking projections composed of a pair of pins set firmly and
spaced from each other laterally of the moving direction of the
lens assembly 74, namely a first linking projection 234 and a
second linking projection 236, are provided on the upper surface of
the driven member 178. The interlocking member 232 has formed
therein a first linking slot 238 and a second linking slot 240
adapted for receiving the first and second linking projections 234
and 236 respectively. The first linking slot 238 extends in an
arcuate shape having the second linking projection 236 as a center,
and the second linking slot 240 extends in an arcuate shape having
the first linking projection 234 as a center. Accordingly, with
regard to the driven member 178, the interlocking member 232 can
pivot about the first linking projection 234 as a center over an
angular range defined by the second linking slot 240, and also
about the second linking projection 236 as a center over an angular
range defined by the first linking slot 238. On the upper surface
of the interlocking member 232 are set up firmly a first engaging
pin 242 and a second engaging pin 244 in relation to the first
linking slot 238 and the second linking slot 240, respectively. The
pull spring member 228 is connected to the first linking projection
234 provided in the driven member 178 and the first engaging pin
242 provided in the interlocking member 232, and the pull spring
member 230 is connected to the second linking projection 236
provided in the driven member 178 and the second engaging pin 244
provided in the interlocking member 232. The pull ring member 228
elastically biases the interlocking member 232 clockwise as seen
from above in FIG. 3 about the second linking projection 236 as a
center with respect to the driven member 178, and the pull spring
member 230 elastically biases the interlocking member 232 clockwise
as viewed from above in FIG. 3 about the first interlocking
projection 234 as a center with respect to the driven member 178.
Thus, normally, the interlocking member 232 is elastically held at
the interlocking relation position shown in FIG. 3 by the pull
springs 228 and 230 with respect to the driven member 178.
An engaging slot 246 extending substantially at right angles to,
and across, the pair of linear running sections 226a and 226b of
the wrapping power transmission member 226 is formed in the central
portion of the interlocking member 232. On the other hand, an
interlocking projection 248 composed of a cylindrical member is set
up in the wrapping power transmission member 226. As is clearly
shown in FIG. 3, the interlocking member 232 is engaged with the
interlocking projection 248 by inserting the interlocking
projection 248 in the engaging slot 246. Thus, as will be stated
hereinbelow, when the wrapping power transmission member 226 is
driven, the interlocking member 232 is moved incident to the
movement of the wrapping power transmission member 226. As will be
understood from FIG. 3, an opening 250 nearly in the shape of a
parallelogram is formed in the driven member 178, and the
interlocking projection 248 set up in the wrapping power
transmission member 226 is inserted in the engaging slot 246 formed
in the interlocking member 232 through the opening 250. As will be
described hereinbelow, when the interlocking member 232 turns from
the interlocking relation position shown in FIG. 3 about the first
linking projection 234 or the second linking projection 236 with
respect to the driven member 178 against the elastic biasing action
of the interlocking spring member composed of the pull springs 228
and 230, the linking projection 248 moving together with the
interlocking member 232 with respect to the driven member 178 moves
within the opening 250 formed in the driven member 178 and does not
directly act on the driven member 178.
In the illustrated embodiment, a position setting means 252 is
disposed in relation to the lens assembly 74. The illustrated
position setting means 252 is constructed of an elongated member
extending in the moving direction of the lens assembly 74. At one
end of the position setting means 252 is formed a projecting
portion 254 projecting widthwise. The projecting portion 254 is
mounted pivotally on an upstanding shaft 256 set up firmly in the
base plate 6 (FIG. 1). A downwardly extending suspending portion
258 is formed at the other end of the position setting means 252,
and corresponding to the suspending portion 258, a stop member 260
having an upstanding portion is fixed to the base plate 6 (FIG. 1).
The above base plate 6 also has an engaging pin 262 set firmly
therein, and a pull spring member 264 is stretched between the
engaging pin 262 and the other end portion of the position setting
means 252. The pull spring member 264 elastically biases the
position setting means 252 counterclockwise as seen from above in
FIG. 3 about the upstanding shaft 256 as a center, and thus, the
position setting means 252 is normally maintained elastically by
the pull spring member 264 at an operating position shown in FIG. 3
at which the suspending portion 258 abuts against the upstanding
portion of the stop member 260. In addition to the projection
portion 254, the position setting means 252 also has a projecting
portion 266 formed in the vicinity of its other end portion, and a
projecting portion 268 formed midway between its opposite ends. As
will be clear from the following description, the inside edge 270
of the projecting portion 254, the inside edge 272 of the
projecting portion 266 and both side edges 274 and 276 of the
projecting portion 268 constitute a stop portion for positioning
the lens assembly 74 at a required position. The inside edge 270 of
the projecting portion 254 and the inside edge 272 of the
projecting portion 266 are located on opposite ends of the moving
path of the lens assembly 74, and the both side edges 274 and 276
of the projecting portion 268 are located in a middle portion in
the moving path of the lens assembly 74. The inside edge 270 of the
projecting portion 254 corresponds to an enlargement position (the
position shown by the two-dot chain line 74E in FIG. 1) of the lens
assembly 74; one side edge 274 of the projecting portion 268, to a
1:1 ratio position (the position shown by the solid line in FIG. 1)
of the lens assembly 74; the other side edge 276 of the projecting
portion 268, to a first reduction position (the position shown by
the two-dot chain line 74R.sub.1 in FIG. 1) of the lens assembly
74; and the inside edge 272 of the projecting portion 266, to a
second reduction position (the position shown by the two-dot chain
line 74R.sub.2 in FIG. 1) of the lens assembly 74. The position
setting means 252 further has an upstanding portion 278. As clearly
shown in FIG. 3, the upstanding portion 278 is cut at one end
portion of the position setting means 252.
In relation to the position setting means 252 described above, an
abutting projection 280 is provided in the lens assembly 74, and a
releasing projection 282 constituting a releasing means is provided
in the interlocking member 232. In the illustrated embodiment, the
abutting projection 280 is composed of a pin set up firmly in the
under surface of the driven member 178, and the releasing
projection 282 is constructed of a pin set firmly in the under
surface of the interlocking member 232. The mutual actions of the
position setting means 252 and the abutting projection 280 and the
releasing projection 282 will be described in detail
hereinafter.
The second drivingly connecting means interposed between the gear
204 and the setting member 134 will now be described. The cam plate
208 which constitutes the input element of the second drivingly
connecting means has formed on its peripheral surface four arcuate
positioning surfaces 284, 286, 288 and 290 and transition surfaces
292, 294, 296 and 298 located among these arcuate positioning
surfaces. The four arcuate positioning surfaces 284, 286,288 and
290 have the shape of an arc having the central axis of rotation of
the cam plate 208 (i.e., the central axis of the rotating shaft 206
to which the cam plate 208 is fixed) although they have different
radii from each other. As will be clear from the following
description, the arcuate positioning surface 284 holds the second
reflecting mirror assembly 72 at the 1:1 ratio position (shown by
the solid line in FIG. 1); the arcuate positioning surface 286, at
the second reduction position (shown by the two-dot chain line
72R.sub.2 in FIG. 1); the arcuate positioning surface 288, at the
first reduction position (shown by the two-dot chain line 72R.sub.1
in FIG. 1); and the arcuate positioning surface 290, at the
enlargement position (shown by the two-dot chain line 72E in FIG.
1).
A projecting portion 300 is formed at one end portion of the
setting member 134, and a follower roller 302 constituring a cam
follower member is rotatably mounted on the projecting portion 300.
An engaging pin 304 is set up firmly in the setting member 134, and
a pull spring member 306 is connected to the engaging pin 304 and
the support shaft 140 set firmly in the upstanding base plate (not
shown) disposed within the housing 2 (FIG. 1). The pull spring
member 306 elastically biases the setting member 134 in the
direction of arrow 150, and thus causes the follower roller 302 to
abut elastically against the cam plate 208. Accordingly, it will be
appreciated that when the cam plate 208 is rotated and the follower
roller 302 is caused to abut against any one of the transition
surfaces 292, 294, 296 and 298, the setting member 134 is moved in
the direction of arrow 150 or 152, and while the follower roller
302 is caused to abut against any one of the arcuate actuating
surfaces 284, 286, 288 and 290, the setting member 134 is
maintained at a spedified position without being moved. When the
setting member 134 is moved in the direction of arrow 150 or 152,
the second reflecting mirror assembly 72 (FIG. 2) is moved in the
direction of arrow 150 or 152, as already described hereinabove
with reference to FIG. 2.
As stated above, the detection plate 210 is also fixed to the
rotating shaft 206 to which the gear 204, the toothed pulley 212
and the cam plate 208 are fixed. As will be readily understood from
FIG. 4-A taken in conjunction with FIG. 3, the detection plate 210
is of a disc shape, and four cuts 308, 310, 312 and 314 are formed
in its peripheral edge portion at predetermined intervals in the
circumferential direction. A light shielding member 316 is also
fixed to the detection plate 210. In relation to the detection
plate 210, two detectors, i.e. a first detector 318 and a second
detector 320 (see FIG. 4-A as these devices are omitted in FIG. 3),
are provided. The first detector 318 has a light emitting element
and a light receiving element located at opposed positions above
and below the peripheral edge portion of the detection plate 210.
When the light from the light emitting element is shut off by the
peripheral edge portion of the detection plate 210 and is not fed
to the light receiving element, the first detector 318 produces an
output signal "H". When any one of the cuts 308, 310, 312 and 314
is positioned between the light emitting element and the light
receiving element and as a result the light from the light emitting
element falls upon the light receiving element, the first detector
318 produces an output signal "L". The second detector 320 has a
light emitting element and a light receiving element positioned
opposite to each other above and below the light shielding member
316 fixed to the detection plate 210, and produces an output signal
"L" when the light from the light emitting element falls upon the
light receiving element without being shut off. The second detector
320 produces an output signal "H" when the light from the light
emitting element is shut off as a result of positioning of the
light shielding member 316 between the light emitting element and
the light receiving element and no longer falls upon the light
receiving element.
Now, the operation and effect of the projecting ratio varying means
182 described above will be stated in detail with reference to
FIGS. 4-A, 4-B, 4-C, 4-D and 4-E taken in conjunction with FIGS. 1
to 3.
As will be described hereinbelow, in the illustrated embodiment,
when the lens assembly 74 and the second reflecting mirror assembly
72 are moved in order to vary the projecting ratio of the optical
system 60, the driving source 184 of the projecting ratio varying
means 182 is rotated in a predetermined direction to rotate the
gear 204 in the direction shown by an arrow 322. Accordingly, the
wrapping power transmission member 226 in the first drivingly
connecting means is moved in the direction of arrow 322, and the
cam plate 208 in the second drivingly connecting means is rotated
in the direction of arrow 322.
For the convenience of description, let us assume that the lens
assembly 74 is at the position shown in FIG. 3. When the wrapping
power transmission member 226 is moved in the direction of arrow
322 in such a state, the movement of the wrapping power
transmission member 226 is transmitted from the interlocking
projection 248 to the lens assembly 74 through the interlocking,
member 232, the spring members 228 and 230 and the driven member
178, and thus, the interlocking member 232, the spring members 228
and 230, the driven member 178 and the lens assembly 74 are moved
as a unit in the direction of arrow 150.
When the lens assembly 74 is moved in the direction of arrow 150
and reaches the 1:1 ratio position shown in FIG. 4-A (the 1:1 ratio
position shown by the solid line in FIG. 1), the abutting
projection 280 provided at the under surface of the driven member
178 abuts against one side edge 274 of the projecting portion 268
of the position setting means 252, thereby preventing the driven
member 178 and the lens assembly 74 from further moving in the
direction of arrow 150. But even when the lens assembly 74 and the
second reflecting mirror assembly 72 are positioned at the 1:1
ratio position, the driving source 184 does not stop rotating upon
abutting of the abutting projection 280 against the side edge 274
of the projecting portion 268 of the position setting means 280,
and the wrapping power tramsmission member 226 continues to be
moved in the direction of arrow 322. When the wrapping power
transmission member 226 is further moved in the direction of arrow
322, this motion of the wrapping power transmission member 226 is
transmitted from the interlocking projection 248 to the
interlocking member 232. As a result, by abutting of the abutting
projection 280 against the side edge 274 of the projecting portion
268, the driven member 178 is prevented from moving further in the
direction of arrow 150. Hence, the interlocking member 232 is
pivotally displaced with respect to the driven member 178 in the
direction of an arrow 324 about the first interlocking projection
234 provided in the driven member 178 as a center against the
elastic biasing action of the spring member 230 from the position
shown by a two-dot chain line in FIG. 4-A (the interlocking
position with respect to the driven member 178) to the position
shown by the solid line in FIG. 4-A. When the interlocking member
232 continues to be pivotally displaced in the direction of arrow
324 with respect to the driven member 178 by the further movement
of the wrapping power transmission member 226 in the direction of
arrow 322, the releasing projection 282 provided on the under
surface of the interlocking member 232 acts on the upstanding
portion 278 of the position setting means 252 to pivot the position
setting means 252 in the direction of an arrow 326 about the
upstanding shaft 256 as a center against the elastic biasing action
of the spring member 264 from its operating position shown by the
solid line in FIG. 4-A and a two-dot chain line in FIG. 4-B to its
releasing position shown by a solid line in FIG. 4-B, as will be
readily understood from a comparison of FIG. 4-A with FIG. 4-B.
When the position setting means 252 is held at the releasing
position shown by the solid line in FIG. 4-B, the side edge 274 of
the projecting portion 268 moves away from the abutting projection
280, and therefore, the driven member 178 and the lens assembly 74
can move from the 1:1 ratio position shown in FIG. 4-A further in
the direction of arrow 150. After this, the interlocking member
232, the spring members 228 and 230, the moving member 178 and the
lens assembly 74 are moved in the direction of arrow 150 according
to the movement of the wrapping power transmission member 226 in
the direction of arrow 322. At this time, the interlocking member
232 and the driven member 178 are returned to the interlocking
relation position shown in FIG. 3 by the elastic biasing action of
the spring member 230. In more detail, the elastic biasing action
of the spring member 230 moves the driven member 178 and the lens
assembly 74 somewhat in the direction of arrow 150 relative to the
interlocking member 232, whereby the interlocking member 232 is
pivotally displaced relative to the driven member 178 in a
direction opposite to the direction of arrow 324 about the first
linking projection 234 as a center and thus the interlocking member
232 and the driven member 178 are returned to the interlocking
relation position illustrated in FIG. 3. When the driven member 178
and the lens assembly 74 move in the direction of arrow 150 and the
abutting projection 280 goes past the projecting portion 268 of the
position setting means 252, the position setting means 252 is
returned to the operating position shown by the solid line in FIG.
4-A and the two-dot chain line in FIG. 4-B by the elastic biasing
action of the spring member 264.
When the lens assembly 74 and the second reflecting mirror assembly
72 are to be positioned at the 1:1 ratio position, the rotation of
the dirving source 184 is stopped at a suitable point in time, for
example at a point shown by the solid line in FIG. 4-A at which the
interlocking member 232 has been pivotally displaced to some extent
with respect to the driven member 178, during the time period from
the time when the abutting projection 280 provided on the under
surface of the driven member 178 has abutted against the side edge
274 of the projecting portion 268 of the position setting means 252
held at this operating position to the time shown in FIG. 4-B, i.e.
the time when the interlocking member 232 has been pivotally
displaced with respect to the driven member 178 and the releasing
projection 282 has moved the position setting means 252 to the
releasing position. At the time shown in FIG. 4-A, the abutting
projection 280 provided on the under surface of the driven member
178 is elastically maintained in condition for abutting against the
side edge 274 of the projecting portion 268 of the position setting
means 252 by the elastic biasing action of the spring member 230,
and thus the lens assembly 74 is accurately held elastically at the
1:1 ration position.
On the other hand, in the state shown in FIG. 4-A, the cam plate
208 is positioned at an agular position at which the arcuate
positioning surface 284 acts on the follower roller 302. As a
result, the setting member 134 is accurately positioned at a
predetermined position, and the second reflecting mirror assembly
72 is accurately held at the 1:1 ratio position shown by the solid
line in FIG. 1. At the time when the rotation of the driving source
184 is stopped, it is not necessary for the cam plate 208 to be
precisely held at a predetermined angular position. If only the cam
plate 208 is positioned at an angular position at which the arcuate
positioning surface 284 acts on the follower roller 302, the
setting member 134 is accurately held at a predetermined position
and the second reflecting mirror assembly 72 is accurately held at
the 1:1 ratio position shown by the solid line in FIG. 1.
In the state shown in FIG. 4-A, the detection plate 210 rotating as
a unit with the cam plate 208 is held at an angular position at
which the cut 308 is detected by the first detector 138 and the
light shielding member 316 is detected by the second detector 320.
Hence, the first detector 318 produces an output signal "L", and
the second detector 320, an output signal "H". The output signals
of the first and second detectors 318 and 320 are used to control
the driving source 184 of the projecting ratio varying means 182 as
will be stated hereinafter.
When the driving source 184 is further rotated and the wrapping
power transmission member 226 is further moved in the direction of
arrow 322, after going through the state shown in FIG. 4-B from the
state shown in FIG. 4-A, the interlocking member 232, the spring
members 228 and 230, the driven member 178 and the lens assembly 74
are moved in the direction of arrow 150 according to the movement
of the wrapping power transmission member 226 in the direction of
arrow 322. When the lens assembly 74 is held at the second
reduction position shown in FIG. 4-C (the position shown by the
two-dot chain line 74R.sub.2 in FIG. 1), the abutting projection
provided at the under surface of the driven member 178 abuts
against the inside edge 272 of the projecting portion 266 of the
position setting means 252, and thus, the driven member 178 and the
lens assembly 74 are prevented from moving further in the direction
of arrow 150. However, even when the lens assembly 74 and the
second reflecting mirror assembly 72 are held at the second
reduction position, the rotation of the driving source 184 is not
stopped at the time when the abutting projection 280 abuts against
the inside edge 272 of the projecting portion 266 of the position
setting means 252, and the wrapping power transmission member 226
continues to move in the direction of arrow 322. It will be readily
appreciated with reference to FIG. 4-C that in such a movement of
the wrapping power transmission member 226, the interlocking
projection 248 set firmly in the wrapping power transmission member
226 moves from one linear running section 226a of the wrapping
power transmission member 226 to the other linear running section
226b through the surrounding of the driven wheel 218. Hence the
interlocking member 232 moving incidental to the interlocking
projection 248 moves in the direction of arrow 150 and then in an
opposite direction, i.e. the direction of arrow 152. Since at this
time the driven member 178 is prevented from moving in the
direction of arrow 150 as a result of the abutting projection 280
abutting against the inside edge 272 of the projecting portion 266,
the interlocking member 232 is pivotally displaced with respect to
the driven member 178 from the interlocking relation position shown
in FIG. 3 in the direction of arrow 324 about the first linking
projection 234 provided in the driven member 178 as a center
against the elastic biasing action of the spring member 230 as
shown in FIG. 4-C according to the movement of the interlocking
member 232 in the direction of arrow 150. Then, as the interlocking
member 232 moves in the direction of arrow 152, it is pivotted in a
direction opposite to the direction of arrow 324 about the first
linking projection 234 as a center, and thus returned to the
interlocking relation position as shown in FIG. 3 with respect to
the driven member 178. During the above pivoting of the
interlocking member 232 with respect to the driven member 178, the
releasing projection 282 provided in the under surface of the
interlocking member 232 never acts on the position in setting
member 252 because as can be easily seen from FIG. 4-C, the
releasing projection 282 exists on the left side of the position
setting means 252 beyond its other end. Thereafter, the
interlocking member 232, the spring members 228 and 230, the driven
member 178 and the lens assembly 74 are moved in the direction of
arrow 152 according to the movement of the wrapping power
transmission member 226 in the direction of arrow 322.
When the lens assembly 74 and the second reflecting mirror assembly
72 are positioned at the second reduction position, the rotation of
the driving source 184 is stopped at a suitable point in time, for
example at the time point shown in FIG. 4-C at which the
interlocking member 232 has pivoted somewhat with respect to the
driven member 178, during the time period from the time when the
abutting projection 280 provided on the under surface of the driven
member 178 has abutted against the inner side edge 272 of the
projecting portion 266 of the position setting means 252 to the
time when the interlocking member 232 pivotally displaced with
respect to the driven member 178 has been returned to the
interlocking relation position with respect to the driven member
178. At the time point shown in FIG. 4-C, the abutting projection
280 is elastically maintained in condition for abutting against the
inside edge 272 of the projecting portion 266 of the position
setting means 252 by the elastic biasing action of the spring
member 230, and thus, the lens assembly 74 is accurately held
elastically at the second reduction position.
While the lens assembly 74 is moved from the 1:1 ratio position
illustrated in FIG. 4-A to the second reduction position shown in
FIG. 4-C, the cam plate 208 is rotated from the angular position
shown in FIG. 4-A to the angular position shown in FIG. 4-C at
which the arcuate positioning surface 286 acts on the follower
roller 302. During this rotation of the cam plate 208, the setting
member 134 is moved from the position shown in FIG. 4-A in the
direction of arrow 152 by the action of the transition surface of
the cam 208, and then held accurately at the position shown in FIG.
4-C by the action of the arcuate positioning surface 286. As a
result, the second reflecting mirror assembly 72 is moved from the
1:1 ratio position shown by the solid line in FIG. 1 to the second
reduction position shown by the two-dot chain line 72R.sub.2 in
FIG. 1 and positioned accurately at this second reduction
position.
The detection plate 210 rotating as a unit with the cam plate 208
is rotated from the angular position shown in FIG. 4-A to the
angular position shown in FIG. 4-C. When the detection plate 210 is
held at the angular position shown in FIG. 4-C, the first detector
318 detects the cut 310 and produces an output signal "L". The
second detector 320, on the other hand, does not detect the light
shielding member 316, and therefore produces an output signal
"L".
When the driving source 184 is further rotated and the wrapping
power transmission member 226 is further moved in the direction of
arrow 322, the interlocking member 232, the spring members 228 and
230, the driven member 178 and the lens assembly 74 are moved in
the direction of arrow 152 according to the movement of the
wrapping power transmission member 226 in the direction of arrow
322. When the lens assembly 74 is held at the first reduction
position shown in FIG. 4-D (the reduction position shown by the
two-dot chain line 74R.sub.1 in FIG. 1), the abutting projection
280 provided on the under surface of the driven member 178 abuts
against the other side edge 276 of the projecting portion 268 of
the position setting means 252, whereby the driven member 178 and
the lens assembly 74 are prevented from moving in the direction of
arrow 152. However, even when the lens assembly 74 and the second
reflecting mirror assembly 72 are held at the first reduction
position, the rotation of the driving source 184 is not stopped
when the abutting projection 280 has abutted against the other side
edge 276 of the projecting portion 268 of the position setting
means 252, and the wrapping power transmission member 226 continues
to move in the direction of arrow 322. When the wrapping power
tramsmission member 226 is further moved in the direction of arrow
322, the movement of the wrapping power transmission member 226 is
transmitted to the interlocking member 232 from the interlocking
projection 248. As a result, since the driven member 178 is
prevented from moving further in the direction of arrow 152 as a
result of the abutting projection 280 abutting against the other
side edge 276 of the projecting portion 268, the interlocking
member 232 is pivotally displaced with respect to the driven member
178 in the direction of an arrow 328 about the second linking
projection 236 provided in the driven member 178 against the
elastic biasing action of the spring member 228, as shown in FIG.
4-D. When the interlocking member 232 continues to be pivotally
displaced in the direction of arrow 328 with respect to the driven
member 178 by the further movement of the wrapping power
transmission member 226 in the direction of arrow 322, the
releasing projection 282 provided on the under surface of the
interlicking member 232 acts on the upstanding portion 278 of the
position setting means 252. Consequently, the position setting
means 252 is pivoted from its operating position shown in FIG. 4-D
to its non-operating position (see the position shown by the solid
line in FIG. 4-B) at which the other side edge 276 of the
projecting portion 268 moves away from the abutting projection 280,
about the upstanding shaft 256 as a center against the elastic
biasing action of the spring member 264 in the same way as
described with reference to FIG. 4-B. Thereafter, the driven member
178 and the lens assembly 74 can move further in the direction of
arrow 152 from the first reduction position shown in FIG. 4-D, and
therefore, the interlocking member 232, the spring members 228 and
230, the driven member 178 and the lens assembly 74 are moved in
the direction of arrow 152 according to the movement of the
wrapping power tramsmission member 226 in the direction of arrow
322. At this time, the interlocking member 232 and the driven
member 178 are returned to the interlocking relation position shown
in FIG. 3 by the elastic biasing action of the spring member 228.
When the driven member 178 and the lens assembly 74 move in the
direction of arrow 152 and the abutting projection 280 goes past
the projecting portion 268 of the position setting means 252, the
position setting means 252 is returned to the operation position
shown in FIG. 4-D by the elastic biasing action of the spring
member 264.
When the lens assembly 74 and the second reflecting mirror assembly
72 are held at the first reduction position, the rotation of the
driving source 184 is stopped at a suitable point in time, for
example the time point shown in FIG. 4-D at which the interlocking
member 232 has been pivotally displaced to some extent with respect
to the driven member 178, during the time period from the time when
the abutting projection 280 provided on the under surface of the
driven member 178 has abutted against the other side edge 276 of
the projecting portion 268 of the position setting means 252 which
is at the operating position to the time when the interlocking
member 232 has been pivotally displaced with respect to the driven
member 178 as described above and the releasing projection 282 has
brought the position setting means 252 to the releasing position.
At the time point shown in FIG. 4-D, the abutting projection 280
formed on the under surface of the driven member 178 is elastically
maintained in condition for abutting against the other side edge
276 of the projecting portion 268 of the position settting means
252 by the elastic biasing action of the spring member 228, and
thus, the lens assembly 74 is elastically held accurately at the
first reduction position.
While the lens assembly 74 is moved from the second reduction
position shown in FIG. 4-C to the first reduction position shown in
FIG. 4-D, the cam plate 208 is rotated from the angular position
shown in FIG. 4-C to the angular position shown in FIG. 4-D at
which the arcuate positioning surface 288 acts on the follower
roller 302. During such a rotation of the cam plate 208, the
setting member 134 is moved from the position shown in FIG. 4-C in
the direction of arrow 150 by the action of the transition surface
294 of the cam plate 208, and is accurately held at the position
shown in FIG. 4-D by the action of the arcuate positioning surface
288. As a result, the second reflecting mirror assembly 72 is moved
from the second reduction position shown by the two-dot chain line
72R.sub.2 shown in FIG. 1 to the first reduction position shown by
the two-dot chain line 72R.sub.1 in FIG. 1 and accurately
positioned at the first reduction position.
The detection plate 210 rotating as a unit with the cam plate 208
is rotated from the angular position shown in FIG. 4-C to the
angular position shown in FIG. 4-D. When the detection plate 210 is
held at the angular position shown in FIG. 4-D, the first detector
318 detects the recess 312 and thus produces an output signal "L".
On the other hand, the second detector 320 does not detect the
light shielding member 316 and therefore, produces an output signal
"L".
When the driving source 184 is further rotated and the wrapping
power transmission member 226 is moved further in the direction of
arrow 322, the interlocking member 232, the spring members 228 and
230, the driven member 178 and the lens assembly 74 are moved in
the direction of arrow 152 according to the movement of the
wrapping power transmission member 226 in the direction of arrow
322 as stated above. When the lens assembly 74 is brought to the
enlargement position shown in FIG. 4-E (the position shown by the
two-dot chain line 74E in FIG. 1), the abutting projection 280
provided on the under surface of the driven member 178 abuts
against the insdie edge 270 of the projecting portion 254 of the
position setting means 252, whereby the driven member 178 and the
lens assembly 74 are prevented from moving further in the direction
of arrow 152. However, even when the lens assembly 74 and the
second reflecting mirror assembly 72 are positioned at the
enlargement position, the rotation of the driving source 184 is not
stopped when the abutting projection 280 has abutted against the
inside edge 270 of the projecting portion 254 of the position
setting means 252, and the wrapping power transmission member 226
continues to be moved further in the direction of arrow 322. It is
readily appreciated from FIG. 4-E that during this movement of the
wrapping power transmission member 226, the interlocking projection
248 set up firmly in the wrapping power transmission member 226
moves from the linear running section 226b to the linear running
section 226a through the surrounding of the driven wheel 222.
Hence, the interlocking member 232 moving incident to the
interlocking projection 248 moves in the direction of arrow 152 and
then in an opposite direction, i.e. in the direction of arrow 150.
Since at this time, the driven member 178 is prevented from moving
in the direction of arrow 152 as a result of the abutting
projection 280 abutting against the inside edge 270 of the
projecting portion 254, the interlicking member 232 is pivotally
displaced with respect to the driven member 178 in the direction of
arrow 328 about the second linking projection 236 provided in the
driven member 178 against the elastic biasing action of the spring
member 228 as shown in FIG. 4-E from the interlocking relation
position shown in FIG. 3 as the interlocking member 232 is moved in
the direction of arrow 152. Thereafter, as it moves in the
direction of arrow 150, the interlicking member 232 is pivoted in a
direction opposite to the direction of arrow 328 about the second
linking projection 236 as acenter, and thus returned to the
interlocking relation position shown in FIG. 3 with respect to the
driven member 178. It will be readily seen from FIGS. 3 and 4-E
that during the aforesaid pivoting of the interlicking member 232
with respect to the driven member 178, the releasing projection 282
provided on the under surface of the interlocking member 232 passes
through the cut portion at one end portion of the upstanding
portion 278 of the position setting member 252, and therefore never
acts on the position setting means 252. Thereafter, the
interlocking member 232, the spring members 228 and 230, the driven
member 178 and the lens assembly 74 are moved in the direction of
arrow 150 according to the movement of the wrapping power
transmission member 226 in the direction of arrow 322.
When the lens assembly 74 and the second reflecting mirror assembly
72 are held at the enlargement position, the rotation of the
driving source 184 is stopped at a suitable point in time, for
example at the time point shown in FIG. 4-E at which the
interlocking member 232 has been pivotally displaced to some extent
with respect to the driven member 178, during the time period
between the time when the abutting projection 280 provided on the
under surface of the driven member 178 has abutted against the
inside edge 270 of the projecting portion 254 of the position
setting means 252 to the time when the interlocking member 232
pivotally displaced with respect to the driven member 178 as
described above has been returned to the interlocking relation
position with respect to the driven member 178. At the time point
shown in FIG. 4-E, the abutting projection 280 provided on the
under surface of the driven member 178 is elastically maintained in
condition for abutting against the inside edge 270 of the
projecting portion 254 of the position setting means 252 by the
elastic biasing action of the spring member 228, and thus the lens
assembly 74 is elastically held accurately at the enlargement
position.
While the lens assembly 74 is moved from the first reduction
position shown in FIG. 4-D to the enlargement position shown in
FIG. 4-E, the cam plate 208 is rotated from the angular position
shown in FIG. 4-D to the angular position shown in FIG. 4-E at
which the arcuate positioning surface 290 acts on the follower
roller 302. During such a rotation of the cam plate 208, the
setting member 134 is moved from the position shown in FIG. 4-D in
the direction of arrow 150 by the action of the transition surface
296 of the cam plate 208, and accurately held at the position shown
in FIG. 4-E by the action of the arcuate positioning surface 290.
Consequently, the second reflecting mirror assembly 72 is moved
from the first reduction position shown by the two-dot chain line
72R.sub.1 in FIG. 1 to the enlargement position shown by the
two-dot chain line 72E in FIG. 1 and accurately held at this
enlargement position.
The detection plate 210 rotating as a unit with the cam plate 208
is rotated from the angular position shown in FIG. 4-D to the
angular position shown in FIG. 4-E. When the detection plate 210 is
brought to the angular position shown in FIG. 4-E, the first
detector 318 detects the cut 314 and therefore produces an output
signal "L". On the other hand, the second detector 320 does not
detect the light shielding member 316, and therefore, produces an
output signal "L".
When the driving source 184 is further rotated and the wrapping
power transmission member 226 is moved further in the direction of
arrow 322, the interlocking member 232, the spring members 228 and
230, the driven member 178 and the lens assembly 74 are moved in
the direction of arrow 150 according to the movement of the
wrapping power transmission member 226 in the direction of arrow
322, as stated hereinabove. At this time, the cam plate 208 is
rotated from the angular position shown in FIG. 4-E toward the
angular position shown in FIG. 4-A. During such a rotation of the
cam plate 208, the setting member 134 is moved from the position
shown in FIG. 4-E toward the position shown in FIG. 4-A in the
direction of arrow 150 by the cooperative action of the transition
surface 298 of the cam plate 208 and the spring member 306 (FIG.
3).
The projecting ratio varying means 182 described above has various
excellent advantages among which are:
(a) Both the lens assembly 74 and the second reflecting mirror
assembly 72 can be positioned at a desired position selected from a
plurality of positions by a relatively simple and cheap
construction having the single driving source 184.
(b) Even when some error exists in the time of stopping the
rotation of the driving source 184, the lens assembly 74 and the
second reflecting mirror assembly 72 can be held accurately at the
desired positions.
In the illustrated specific embodiment, the position setting means
252 is formed of a single material, but if desired, it may be
constructed of a plurality of members mounted independently from
each other. Furthermore, in the illustrated embodiment, the
position setting means is moved from the operating position to the
releasing position by the action of the releasing projection 282
provided in the interlocking means 232. If desired, however, it is
possible to provide a releasing means such as a solenoid in
relation to the position setting means 252 and move the position
setting means 252 at a desired time from the operating position to
the releasing position by selectively actuating the releasing means
(in which case, however, the component parts are likely to undergo
damage when the releasing means is not acutated at the required
time for some reason or other). Furthermore, when there are only
two projecting magnification ratios to he selectively set and
therefore it is only sufficient to position the lens assembly 74
(and the second reflecting mirror assembly 72) at one of the two
positions, the necessity of moving the position setting means from
the operating position to the releasing position can be obviated if
the aforesaid two positions are set at the opposite ends of the
moving path of the lens assembly 74.
One example of controlling the operation of the driving source 184
of the projecting ratio varying means 182 will now be described
mainly with reference to the simplified block diagram shown in FIG.
5.
The illustrated variable magnification electrostatic copying
apparatus is constructed such that at whatever positions the lens
assembly 74 and the second reflecting mirror assembly 72 are
positioned (including the case where they are positioned at the 1:1
ratio position shown by the solid line in FIG. 1), when power is
applied to the copying apparatus, the lens assembly 74 and the
second reflecting mirror assembly 72 are moved and positioned
accurately at the 1:1 ratio position shown by the solid line in
FIG. 1. For example, when power is applied to the copying apparatus
by closing a main switch (not shown) provided in the copying
apparatus, a power application signal producing device 330 produces
an output signal and feeds it to a control circuit 332. As a
result, the control circuit 332 feeds a conduction signal to a
first driver 334 to maintain the first driver 334 in conduction.
When the first driver 334 conducts, a normal rotating current is
fed from a power supply 336 to a driving source for the projecting
ratio varying means 182, i.e. the reversible electric motor 184, to
rotate the motor 184 normally. Thus, the gear 204 is rotated in the
direction of arrow 322, the wrapping power transmission member 226
is moved in the direction of arrow 322, and the cam plate 208 is
rotated in the direction of arrow 322. Consequently, the lens
assembly 74 and the second reflecting mirror assembly 72 are moved
as required. When they attain the state shown in FIG. 4-A in which
the lens assembly 74 is held at the 1:1 ratio position shown by the
solid line in FIG. 1 and the second reflecting mirror assembly 72
is held at the 1:1 ratio position shown by the solid line in FIG.
1, the first detector 318 detects the cut 308 of the detection
plate 210 to produce an output signal "L" and feed it to the
control circuit 332, and the second detector 320 detects the light
shielding member 316 of the detection plate 210 to produce an
output signal "H" and feed it to the control circuit 332, as
already stated hereinabove with reference to FIG. 4-A.
Consequently, the control circuit 332 feeds a conduction signal to
a second driver 338 and maintains it in conduction. When the second
driver 338 thus conducts, a relay 340 is energized to reverse the
direction of connection between the power supply 336 and the motor
184, and a reversing current is fed to the motor 184. After the
lapse of some time from the time when the control circuit 332 fed a
conduction signal to the second driver 338, the control circuit 332
feeds a non-conduction signal to the first driver 334 to maintain
it non-conducting and also feeds a non-conduction signal to the
second driver 338 to maintain it non-conducting. Thus, the supply
of current to the motor 184 is stopped, and the relay 340 is
de-energized to return the connecting direction of the power supply
336 and the motor 184 to its original condition. When a reversing
current is instantaneously fed to the normally rotating motor 184
in stopping the operation of the motor 184, the reversing current
supplied instantaneously applies a braking action to the normal
rotation of the motor 184 thereby preventing coasting of the motor
184 owing to inertia and sharply stopping the normal rotation of
the motor 184. Thus, in the state shown in FIG. 4-A, the normal
rotation of the electric motor 184 is stopped, and the lens
assembly 74 and the second reflecting mirror assembly 72 are
accurately held at the 1:1 ratio position shown by the solid line
in FIG. 1.
When after the end of the above initial positioning the operator
depresses a first reduction copying switch R.sub.1, a second
reduction copying switch R.sub.2, or an enlarged copying switch E,
the normal rotation of the motor 184 is started by the control
circuit 332. When the state shown in FIG. 4-D, 4-C or 4-E is
attained, the motor 184 is stopped (upon stopping of the motor 184,
a reversing current is supplied instantaneously to apply a braking
action as described above). Thus, the lens assembly 74 and the
second reflecting mirror assembly 72 are definitely held at the
first reduction positions shown by the two-dot chain lines
74R.sub.1 and 72R.sub.1 in FIG. 1, the second reduction positions
shown by the two-dot chain lines 74R.sub.2 and 72R.sub.2 in FIG. 1,
or the enlargement positions shown by the two-dot chain lines 74E
and 72E in FIG. 1. When the operator depresses a 1:1 ratio copying
switch N while the lens assembly 74 and the second reflecting
mirror assembly 72 are at positions other than the 1:1 positions
shown by the solid line in FIG. 1 (that is, at the first reduction
positions, the second reduction positions or the enlargement
positions), the lens assembly 74 and the second reflecting mirror
assembly 72 are likewise held at the 1:1 ratio positions shown by
the solid lines in FIG. 1. Of course, when the operator depresses
the second reduction copying switch R.sub.2 (or the enlarged
copying switch E or the first reduction copying switch R.sub.1)
while the lens assembly 74 and the second reflecting mirror
assembly 72 are at the first reduction positions (or the second
reduction positions, or the enlargement positions), the lens
assembly 74 and the second reflecting mirror assembly 72 are
likewise held accurately at the second reduction positions (or the
enlargement positions or the first reduction positions). The states
shown in FIGS. 4-C, 4-D and 4-E which correspond to the first
reduction positions, the second reduction positions and the
enlargement positions respectively are detected by using as a
standard the state shown in FIG. 4-A which corresponds to the 1:1
ratio positions. Specifically, the control circuit 332 uses as a
standard the state shown in FIG. 4-A in which the output signal of
the first detector 318 is "L" and the output signal of the second
detector 320 is "H". When from this state, the output signal of the
first detector 318 changes to "H" and thereafter again changes to
"L" as a result of detecting the cut 310 of the detection plate
210, the control circuit 332 detects the occurrence of the state
shown in FIG. 4-C. When the output signal of the first detector 318
changes to "H" and thereafter again changes to "L" as a result of
detecting the cut 312 of the detection plate 210, the control
circuit 332 detects the occurrence of the state shown in FIG. 4-D.
When the output signal of the first detector 318 changes to "H" and
thereafter again changes to "L" as a result of detecting the cut
314 of the detection plate 210, the control circuit 332 detects the
occurrence of the state shown in FIG. 4-E. According to these
detections, the control circuit 332 properly controls the first
driver 334 and the second driver 338.
Driving Means
Now, with reference to FIGS. 6 and 7, driving means shown generally
at 342 in FIG. 6 for reciprocating the first reflecting mirror
assembly 66 and the decond reflecting mirror assembly 72 of the
optical system 60 will be described.
With reference to FIG. 6, a pair of shafts 344 and 346 are provided
with a space therebetween in the reciprocating directions of the
first reflecting mirror assembly 66 and the second reflecting
mirror assembly 72 shown by arrows 150 and 152. The shaft 344 is
set firmly in an upstanding base plate 348 disposed within the
housing 2 (FIG. 1), and the shaft 346 is set firmly in a support
frame 350 fixed to the upstanding base plate 348. Elongated slots
352, 354 and 355 (see FIG. 7 also) extending in the directions of
arrows 150 and 152 are formed respectively at the upper two sides
and the lower center of the support frame 350. By threadably
engaging setscrews 356, 358 and 359 (see FIG. 7 also) with the
upstanding base plate 348 through these slots 352, 354 and 355, the
support frame 350 is fixed to the upstanding base plate 348 so that
its position can be adjusted freely in the directions of arrows 150
and 152. Wheels 360 and 362 which are conveniently sprocket wheels
are rotatably mounted on the shafts 344 and 346. An endless
wrapping power transmission member 364 which is conveniently an
endless chain is wrapped about these wheels 360 and 362. A
cylindrical interlocking projection 366 is set firmly in the
wrapping power transmission member 364. On the other hand, as
already described with reference to FIG. 2, the driven member 116
having a horizontal portion 112 and a suspending portion 114 is
fixed to the first reflecting mirror assembly 66. An engaging slot
368 extending in the vertical direction is formed in the suspending
portion 114 of the driven member 116, and by inserting the
interlocking projection 366 into the engaging slot 368, the driven
member 116 is kept in engagement with the interlocking projection
366. It will be clear therefore that when the interlocking
projection 366 is moved by the driving of the wrapping power
transmission member 364 as described below, the first reflecting
mirror assembly 66 is moved incident to the movement of the
interlocking projection 366.
The shaft 344 having the wheel 360 mounted thereon further has
mounted thereon an additional sprocket wheel 370 adapted for
rotation as a unit with the wheel 360. In relation to the wheel
370, shafts 372 and 374 are set firmly in the upstanding base plate
348. A sprocket wheel 376 is rotatably mounted on the shaft 372,
and a sprocket wheel 378 is rotatably mounted on the shaft 374. An
endless chain 380 is wrapped about the wheels 370, 376 and 378. The
shaft 374 also has mounted thereon a gear 382 adapted for rotation
as a unit with the wheel 378. As shown in a simplified form, the
output side of a power transmission mechanism 386 for forward
movement including four selectively operable forward movement
clutches 384N, 384R.sub.1, 384R.sub.2 and 384E is drivingly
connected to the gear 382. The forward movement clutches 384N,
384R.sub.1, 384R.sub.2 and 384E may, for example, be
electromagnetic clutches. The input side of the forward movement
power transmission mechanism 386 is drivingly connected to a mian
driving source 388.
The support frame 350 is equipped with a backward movement power
transmission mechanism shown generally at 390. The backward
movement power transmission mechanism 390 includes a backward
movement clutch 392 which may be constructed of an electromagnetic
clutch. A sprocket wheel 394 is provided on the input side of the
backward movement clutch 392, and the wheel 394 is drivingly
connected to the main driving source 388 as shown in a simplified
form. A gear 396, on the other hand, is provided on the output side
of the backward movement clutch 392. When the backward movement
clutch 392 is operated, the gear 396 is connected to the wheel 394.
The backward movement power transmission mechanism 390 further
includes a gear 398 in mesh with the gear 396, a gear 400 adapted
for rotation with the gear 398, and a gear 402 in mesh with the
gear 400. The gear 402 is connected to the wheel 362 through a
one-way clutch 404 (which constitutes part of a backward movement
restricting means 406 to be described) having a plurality of
engaging pawls 403 formed on its peripheral surface.
The illustrated driving means 342 further includes the backward
movement restricting means 406 including the one-way clutch 404,
for terminating the backward movement of the first reflecting
mirror assembly 66 and the second reflecting mirror assembly 72
accurately at a predetermined position, i.e. a forward movement
start position. With reference to FIG. 7 taken in conjunction with
FIG. 6, a support member 408 is fixed to the upper end portion of
the support frame 350. Elongated slots 410 and 412 extending in the
directions of arrows 150 and 152 are formed respectively at the two
opposite end portions of the support member 408, and by threadably
engaging setscres 414 and 416 with the support frame 350 through
the slots 410 and 412, the support member 408 is fixed to the
support frame 350 so that its position is freely adjustable in the
directions of arrows 150 and 152. The support member 408 has a pair
of guide wall portions 418 and 420 spaced from each other in the
directions of arrows 150 and 152. The guide wall portions 418 and
420 have formed therein holes which are in alignment in the
directions of arrows 150 and 152. and a rod 422 is slidably
inserted in these holes. A large-diameter head portion 424 is
formed at one end of the rod 422 which is located on the left side
of the guide wall portion 418 in FIG. 7. A block 428 and a
channel-like abutting member 430 located outwardly of the block 428
are fixed by means of a setscrew 426 to that part of the rod 422
which is between the guide wall portions 418 and 420. An elongated
slot 432 extending in the directions of arrows 150 and 152 is
formed in the upper wall portion of the abutting member 430. The
set-screw 426 is threadedly fitted with the rod 422 through the
slot 432, and therefore, the abutting member 430 is fixed to the
rod 422 so that its position is freely adjustable in the directions
of arrows 150 and 152. The lower wall portion of the abutting
member 430 has a projecting portion 434 projecting beneath the
support member 408. A compression spring member 436 is interposed
between the guide wall portion 418 and the block 428. The spring
member 436 elastically biases the rod 422 and the block 428 and the
abutting member 430 fixed thereto to the right in FIG. 7 and
elastically maintains them at a position at which the head portion
424 of the rod 422 abuts against the guide wall portion 418. To the
other end portion of the rod 422 which is located on the right side
of the guide wall portion 420 in FIG. 7 is fixed slidably a
channel-like member 444 having a wall portion 438 extending along
the rod 422 and both end wall portions 440 and 442 extending
substantially perpendicular to the wall portion 438. Furthermore, a
stop ring 446 positioned on the left side of the end wall portion
440 of the member 444 in FIG. 7 and a stop ring 448 located between
the two end wall portions 440 and 442 of the member 444 are also
fixed to the other end portion of the rod 422. A compression spring
member 450 is interposed between the end wall portion 440 of the
member 444 and the stop ring 448. The spring member 450 elastically
biases the member 444 to the left in FIG. 7 with respect to the rod
422 and maintains it elastically at a position at which its end
wall portion 440 abuts against the stop ring 446. On the other
hand, a pin 451 is set up firmly in the support frame 350, and a
clutch control member 452 is pivotally mounted on the pin 451. The
clutch control member 452 has a first arm 454 and a second arm 456.
At the end of the first arm 454 is formed an engaging piece 458
which can engage the engaging pawl 403 formed on the peripheral
surface of the one-way clutch 404. On the other hand, a vertically
extending slot 439 (FIG. 7) is formed at the forward end portion of
the second arm 456. The forward end portion of the second arm 456
is connected to the member 444 by inserting a pin 460 (FIG. 7)
firmly set up in the wall portion 438 of the member 444 into the
slot 439. The backward movement restricting means 406 further
comprises an actuating piece 462 fixed to the wrapping power
transmission member 364.
When the first reflecting mirror assembly 66 and the second
reflecting mirror assembly 72 continue to move backwardly as
described below and reach predetermined forward movement start
positions, the actuating piece 462 fixed to the wrapping power
transmission member 364 in the backward restricting means 406
described hereinabove abuts against the projecting portion 434 of
the abutting member 430 fixed to the rod 422 to move the rod 422
from the position shown by a solid line in FIG. 7 to the position
shown by a two-dot chain line in FIG. 7 against the elastic biasing
action of the spring member 436. As a result, the member 444
mounted on the rod 422 is also moved from the position shown by a
solid line in FIG. 7 to the position shown by a two-dot chain line
in FIG. 7, and the clutch control member 452 is pivoted from its
non-engaging position shown by a solid line in FIG. 7 to its
engaging position shown by a two-dot chain line in FIG. 7. When the
clutch control member 452 is held at the engaging position shown by
the two-dot chain line in FIG. 7, the engaging piece 458 formed at
the forward end of the first arm 454 engages any one of the
engaging pawls 403 formed on the peripheral surface of the one-way
clutch 404, and consequently the one-way clutch 404 is kept
inoperative to release the connection between the gear 402 and the
wheel 362.
On the other hand, when the first reflecting mirror assembly 66 and
the second reflecting mirror assembly 72 start to move forwardly
from the predetermined forward movement start positions as
described hereinbelow, the actuating piece 462 moves away from the
projecting portion 434 of the abutting member 430 fixed to the rod
422, as shown in FIGS. 6 and 7. As a esult, the rod 422 is returned
to the position shown by the solid line in FIG. 7 by the elastic
action of the spring member 436, and the member 444 is also
returned to the position shown by the solid line in FIG. 7. Hence,
the clutch control member 452 is returned to the non-engaging
position shown by the solid line in FIG. 7 from the engaging
position shown by the two-dot chain line in FIG. 7. As a result,
the engaging piece 458 formed at the forward end of the first arm
454 of the clutch control member 452 disengages from the engaging
pawl 403 formed on the peripheral surface of the one-way clutch 404
to maintain the one-way clutch 404 operable. Hence, the gear 402
and the wheel 362 are connected through the one-way clutch 404.
In the illustrated embodiment, the actuating piece 462 is fixed to
the wrapping power transmission member 364. The actuating piece 462
may also be mounted at any other suitable place so long as it can
move the first reflecting mirror assembly 66 and the second
reflecting mirror assembly 72 and when these assemblies are held at
predetermined forward movement start positions, can move the clutch
control member 452 from the non-engaging position to the engaging
position.
In the illustrated embodiment, a light-shielding member 464 having
four upstanding light-shielding portions 464R.sub.2, 464R.sub.1,
464N and 464E and a permanent magnet 466 are fixed to the upper
surface of the horizontal portion 112 of the driven member 116
provided in the first reflecting mirror assembly 66. With regard to
the light-shielding member 464, a first movement detector 468 and a
second movement detector 470 each having a light emitting element
and a light receiving element located opposite to each other are
fixed to predetermined positions of the upstanding base plate 348.
Reed switches 480 and 482 cooperating with the permanent magnet 466
are fixed respectively to brackets 476 and 478 which are fixed to
predetermined positions of the upstanding base plate 348 by
setscrews 472 and 474 respectively.
The operation of the driving means 342 described above will be
summarized below with reference to FIG. 1 taken in conjunction with
FIG. 6.
In the case of 1:1 ratio copying, the forward movement clutch 384N
of the forward movement power transmission mechanism 386 is
selectively operated. The main driving source 388 is connected to
the wheel 360 through the clutch 384N, the gear 382, the wheel 378,
the chain 380 and the wheel 370, whereby the wheel 360 is rotated
in the direction of arrow 484 and the wrapping power transmission
member 364 is moved in the direction of arrow 484. As a result, the
driven member 116, and therefore the first reflecting mirror
assembly 66 (FIGS. 1 and 2), begin to move forwardly in the
direction of arrow 150 from the forward movement start positions
shown by the two-dot chain lines in FIG. 6 in interlocking relation
to the interlocking projection 366 provided in the wrapping power
transmission member 364. When the first reflecting mirror assembly
66 begins its forward movement, the second reflecting mirror
assembly 72 also begins to move forwardly by the existence of the
decelerating interlocking mechanism 118. It will be readily
appreciated that while the interlocking projection 366 moves along
the peripheral edge of the wheel 360, the forward movements of the
first reflecting mirror assembly 66 and the second reflecting
mirror assembly 72 in the direction of arrow 150 are gradually
accelerated. When the interlocking projection 366 begins to move
along the lower linear running section of the wrapping power
transmission member 364, the first reflecting mirror assembly 66 is
moved forward at a predetermined speed V and the second reflecting
mirror assembly 72, at a speed of V/2. When the first reflecting
mirror assembly 66 moves forwardly and the light-shielding portion
464N of the light shielding member 464 is positioned between the
light emitting element and the light receiving element of the first
movement detector 468, the first movement detector 468 detects it
and produces a paper conveying start signal. Thus, the rotation of
the carrying roller unit 44 of the paper conveying mechanism 34
shown in FIG. 1 is started, and the conveying of a copying paper
which has been fed to the nip portion of the carrying roller unit
44 through the delivery passage 42a or 42b and is ready for
conveying is started. In the illustrated embodiment, when the first
reflecting mirror assembly 66 and the second reflecting mirror
assembly 72 have advanced a predetermined distance from the time
when the first movable detector 468 produced a paper conveying
start signal, the scanning exposure of a document placed on the
transparent plate 4 is started, and projection of the image of the
document on the photosensitive member 10 begins. Thereafter, when
the trailing end of the copying paper conveyed by the paper
conveying mechanism 34 goes past a paper detector 488 disposed in
the paper conveying passage, the paper detector 488 produces a
scanning exposure termination signal. The length of the paper
conveying passage from the detecting postion of the paper detector
488 to the transfer zone 28 is made substantially equal to the
length of the moving path of the photosensitive member 10 from the
exposure zone 26 to the transfer zone 28. When the scanning
exposure termination signal is produced, the forward movement
clutch 384N is maintained non-operative to stop the rotation of the
wheel 360 and the forward movement of the first reflecting mirror
assembly 66 and the second reflecting mirror assembly 72.
Simultaneously with, or immediately after, this, the backward
movement clutch 392 of the backward movement power transmission
mechanism 390 is actuated. Thus, the main driving source 388 is
connected to the wheel 362 through the wheel 394, the backward
movement clutch 392, the gears 396, 398, 400 and 402, and the
one-way clutch 404 in an operative condition, whereby the wheel 362
is rotated in the direction of arrow 486 and the wrapping power
transmission member 364 is moved in the direction of arrow 486. As
a result, the first reflecting mirror assembly 66 begins to move
backwardly in the direction of arrow 152 at a speed of, for
example, 2.3V, and the second reflecting mirror assembly 72 begins
to move backwardly in the direction of arrow 152 at a speed of
2.3V/2. When the first reflecting mirror assembly 66 and the second
reflecting mirror assembly 72 continue to move backwardly and
approach their forward movement start positions and the
interlocking projection 366 set up firmly in the wrapping power
transmission member 364 begins to move along the peripheral edge of
the wheel 360, the backward movements of the first and second
reflecting mirror assemblies 66 and 72 in the direction of arrow
152 are gradually decelerated, as will be readily understood. When
the first and second reflecting mirror assemblies 66 and 72 return
to their forward movement start position (namely, when the driven
member 116 returns to the position shown by the two-dot chain line
in FIG. 6), the backward movement restricting means 406 acts as
described above to maintain the one-way clutch 404 inoperative.
Thus, the rotation of the wheel 360 is stopped, and the first and
second reflecting mirror assemblies 66 and 72 are stopped
accurately at the predetermined forward movement start positions.
Substantially simultaneously with this, the second movement
detector 470 detects the light shielding portion 464R.sub.2 of the
light shielding member 464 and produces a backward movement
termination signal. Consequently, after the lapse of some time, the
backward movement clutch 392 is maintained inoperative.
It is possible to omit the backward movement restricting means 406,
and to maintain the backward movement clutch 392 inoperative after
the second movement detector 470 has produced a backward movement
termination signal. This, however, causes the following
inconvenience. When the backward movement clutch 392 is made of an
electromagnetic clutch and is operated repeatedly for a long period
of time, deenergization of the clutch may not sharply render it
inoperable because of the heat generated during the long-term
operation, and some error tends to occur between the time of
deenergization and the time at which the clutch becomes
inoperative. It will be readily understood that if this error
occurs, the backward movement stop positions of the first and
second reflecting mirror assemblies 66 and 72 deviate from their
predetermined forward movement start positions. In contrast, by
using the aforesaid backward movement restricting means 406, the
first and second reflecting mirror assemblies 66 and 72 can be
accurately stopped at the predetermined forward movement start
positions. The backward restricting means 406 having the above
advantage can be applied not only to variable magnification
electrostatic copying apparatuses but also to single magnification
electrostatic copying apparatuses permitting copying only at a 1:1
magnification, for example. It can also be applied to the accurate
and stable stopping of a transparent plate in electrostatic copying
apparatuses of the type in which the transparent plate is
reciprocable.
In the case of the first reduction copying, the forward movement
clutch 384R.sub.1 of the forward movement power transmission
mechanism 386 is selectively operated to start the forward movement
of the first and second reflecting mirror assemblies 66 and 72.
After they are gradually accelerated, the first reflecting mirror
assembly 66 is moved forwardly at a speed of about V/0.83, and the
second reflecting mirror assembly 72 is moved forwardly at a speed
of about V/2.times.0.82. The first movement detector 468 produces a
paper conveying start signal when it detects the light shielding
portion 464R.sub.1 of the light shielding member 464. Otherwise,
the operation is the same as in the case of 1:1 ratio copying.
In the case of the second reduced copying, the forward movement
clutch 384R.sub.2 of the forward movement power transmission
mechanism 386 is selectively operated to start the forward movement
of the first and second reflecting mirror assemblies 66 and 72.
After they are gradually accelerated, the first reflecting mirror
assembly 66 is moved forwardly at a speed of about V/0.7, and the
second reflecting mirror assembly 72, at a speed of about
V/2.times.0.7. The first movement detector 468 produces a paper
conveying start signal when it detects the light shielding portion
464R.sub.2 of the light shielding member 464. Otherwise, the
operation is the same as in the case of 1:1 ratio copying.
In the case of enlarged copying, the forward movement clutch 384E
of the forward movement power transmission mechanism 386 is
selectively operated to start the forward movement of the first and
second reflecting mirror assemblies 66 and 72. After they are
gradually accelerated, the first reflecting mirror assembly 66 is
moved forwardly at a speed of about V/1.27, and the second
reflecting mirror assembly 72, at a speed of about V/2.times.1.27.
The first movement detector 468 produces a paper conveying start
signal when it detects the light shielding portion 464E of the
light shielding member 464. Otherwise, the operation is the same as
in the case of 1:1 ratio copying.
The first movement detector 468 is releated to the light shielding
portions 464N, 464R.sub.1, 464R.sub.2 and 464E of the light
shielding member 464 in the following way. Let the forward movement
distance of the first reflecting mirror assembly 66 from the
position of the first reflecting mirror assembly 66 at the time of
detecting each of the light shielding portions 464N, 464R.sub.1,
464R.sub.2 and 464E of the light shielding member 464 to the
position of the first reflecting mirror assembly 66 (this position
is the same in any of the 1:1 ratio copying, the first reduced
copying, the second reduced copying and the enlarged copying) at
the start of scanning exposure of the document be nl, R.sub.1 l,
R.sub.2 l, or El respectively, the following relation holds good:
Nl.times.1/V.apprxeq.R.sub.1 l.times.0.82/V.apprxeq.R.sub.2
l.times.0.7/V.apprxeq.El.times.1.27/V. Thus, the scanning exposure
of the document is synchronized with the conveying of the copying
paper as required in any of the 1:1 ratio copying, the first
reduced copying, the second reduced copying and the enlarged
copying.
The reed switch 480 illustrated in FIG. 6 defines the forward
movement limit positions of the first and second reflecting mirror
assemblies 66 and 72 in the case of the 1:1 copying, the first
reduced copying, and the second reduced copying. The reed switch
482 shown in FIG. 6 defines the forward movement limit positions of
the first and second reflecting mirror assemblies 66 and 72 in the
enlarged copying mode. When in the 1:1 ratio copying, the first
reduced copying and the second reduced copying, the first and
second reflecting mirror assemblies 62 and 72 continue to move
forwardly because of the inability of the paper detector 488 (FIG.
1) to produce a scanning exposure termination signal owing to paper
jamming, etc. and the permanent magnet 466 provided on the upper
surface of the moving member 116 reaches the position of the reed
switch 480, the reed switch 480 detects it and produces a forward
movement termination signal. In the case of the enlarged copying,
when the first and second reflecting mirror assemblies 66 and 72
continue to move forwardly because of the inability of the paper
detector 488 (FIG. 1) to produce a scanning exposure termination
signal, and the permanent magnet 466 provided on the upper surface
of the moving member 116 reaches the position of the reed switch
482, the reed switch 482 detects it and produces a forward movement
termination signal. When the reed switch 480 or 482 produces a
forward movement termination signal, any one of the forward
movement clutches 384N, 384R.sub.1, 384R.sub.2 and 384E which has
so far been operative is rendeted non-operative to stop the forward
movement of the first and second reflecting mirror assemblies 66
and 72. If desired, it is possible to render the backward movement
clutch 392 operative simultaneously with, or immediately after,
this, and to start the backward movement of the first and second
reflecting mirror assemblies 66 and 72. The reed switch 482 which
acts in the enlarged copying mode is disposed on the side of the
forward movement start positions of the first and second reflecting
mirror assemblies 66 and 72 by a predetermined distance from the
reed switch 480 which acts in the case of the 1:1 ratio copying.
This is for the following reasons.
(a) As can be seen from FIG. 1, in the case of the enlarged
copying, the lens assembly 74 is moved to the side of the forward
movement start positions of the first and second reflecting mirror
assemblies 66 and 72, and therefore, the allowable forward moving
distance of the second reflecting mirror assembly 72 (the distance
over which the mirror assembly 72 can move forward without coming
into collision with the lens assembly 74) becomes shorter.
(b) In the enlarged copying mode, the maximum copyable length of a
document is shorter than the maximum length of a copying paper
conveyed by the paper conveying mechanism 34 (they are
substantially equal in the case of the 1:1 ratio copying, and the
latter is longer than the former in the case of the first and
second reduced copying modes), and therefore, the maximum forward
movement distance required of the first and second reflecting
mirror assemblies 66 and 72 is shorter.
While the present invention has been described hereinabove in
detail with reference to one specific embodiment of the variable
magnification electrostatic copying apparatus with reference to the
accompanying drawings, it should be understood that the present
invention is not limited to this specific embodiment alone, and
various changes and modifications are possible without departing
from the scope of the invention.
* * * * *